📐 Mathematics
Absolute Value
The distance of a number from zero on a number line, ignoring whether it is positive or negative.
Acute Angle
An angle that measures greater than 0° and less than 90°.
Algorithm
A step-by-step set of operations or instructions to be followed in calculations or problem-solving.
Area
The total size of a two-dimensional surface contained within a specific boundary.
Asymptote
A straight line that a curve approaches closer and closer but never quite touches or crosses.
Binomial
An algebraic expression that contains exactly two terms (such as x + y).
Calculus
The branch of mathematics that deals with the finding and properties of derivatives and integrals of functions.
Circumference
The linear distance around the outside edge of a circle.
Coefficient
A number or constant value placed before and multiplying a variable (such as the 4 in 4x).
Denominator
The bottom integer in a fraction that represents the total number of equal parts into which a whole is divided.
Diameter
A straight line passing from one side of a circle to another through its exact center.
Equation
A mathematical statement containing an equals sign (=) to show that two expressions have the same value.
Exponent
A number that tells how many times a base number is multiplied by itself.
Factor
A whole number that divides into another number exactly without leaving a remainder.
Fraction
A part of a whole number, written as one value over another separated by a dividing line.
Geometry
The branch of mathematics that studies the sizes, shapes, positions, and dimensions of things.
Hypotenuse
The longest side of a right-angled triangle, always located directly opposite the right angle.
Integer
Any whole number that can be positive, negative, or zero (with no decimals or fractions).
Matrix
A grid or rectangular array of numbers arranged in horizontal rows and vertical columns.
Mean
The mathematical average of a set of numbers, found by adding them all together and dividing by the total count.
Median
The middle value in a list of numbers sorted in order from smallest to largest.
Mode
The specific number or value that appears most frequently in a given data set.
Numerator
The top integer in a fraction that shows how many parts of the whole are being counted.
Obtuse Angle
An angle that measures greater than 90° but less than 180°.
Parabola
A U-shaped symmetrical curve formed by the graph of a quadratic equation.
Perimeter
The total distance around the outermost edge of a two-dimensional shape.
Abscissa
The horizontal (x) coordinate of a point on the Cartesian plane.
Addend
A number that is added to another number to form a sum.
Algebra
The branch of mathematics that uses symbols and variables to represent numbers and relationships.
Angle Bisector
A ray or line that divides an angle into two equal angles.
Annulus
The region between two concentric circles.
Apothem
The perpendicular distance from the center of a regular polygon to one of its sides.
Arc
A portion of the circumference of a circle.
Arithmetic
The study of numbers and the basic operations of addition, subtraction, multiplication, and division.
Associative Property
A property stating that changing the grouping of numbers does not change the result.
Axis
A reference line used to measure coordinates or symmetry.
Base
The bottom side of a geometric figure or the number raised to a power.
Bijection
A function where every input maps to a unique output and every output has exactly one input.
Boundary
The edge or limit surrounding a geometric region.
Cardinality
The number of elements contained in a set.
Cartesian Plane
A coordinate system formed by perpendicular x- and y-axes.
Center
The point equidistant from every point on a circle or sphere.
Central Angle
An angle whose vertex is at the center of a circle.
Chord
A line segment joining two points on a circle.
Commutative Property
A property stating that changing the order of numbers does not change the result for addition or multiplication.
Complementary Angles
Two angles whose measures add up to 90 degrees.
Complex Number
A number containing both a real part and an imaginary part.
Cone
A three-dimensional shape with one circular base and a single vertex.
Congruent
Having the same size and shape.
Constant
A fixed value that does not change.
Coordinate
A value that identifies the location of a point.
Coordinate Plane
A flat surface formed by two perpendicular number lines.
Coprime
Two integers whose greatest common factor is 1.
Correlation
A measure of the relationship between two variables.
Cube
A three-dimensional solid with six equal square faces.
Cube Root
A number that, when multiplied by itself three times, equals a given value.
Cylinder
A solid with two parallel circular bases connected by a curved surface.
Decimal
A number written using a decimal point to separate whole and fractional parts.
Degree
A unit used to measure angles.
Diagonal
A line segment connecting two non-adjacent vertices of a polygon.
Difference
The result obtained by subtraction.
Digit
Any of the symbols 0 through 9 used to write numbers.
Dimension
A measurable extent such as length, width, or height.
Direct Variation
A relationship where one variable changes proportionally with another.
Dividend
The number being divided.
Divisor
The number by which another number is divided.
Domain
The complete set of possible input values for a function.
Edge
The line where two faces of a solid meet.
Ellipse
A closed curve where the sum of distances to two fixed points is constant.
Empty Set
A set containing no elements.
Estimate
An approximate calculation or value.
Even Number
An integer divisible by 2 without a remainder.
Expression
A mathematical phrase made of numbers, variables, and operations.
Face
A flat surface on a three-dimensional figure.
Finite
Having a limited number of elements or size.
Formula
A mathematical rule expressed using symbols.
Function
A relation where each input has exactly one output.
Geometric Sequence
A sequence where each term is multiplied by the same constant ratio.
Greatest Common Factor
The largest factor shared by two or more numbers.
Hexagon
A polygon with six sides and six angles.
Identity
An equation that is true for all values of its variables.
Imaginary Number
A number involving the square root of negative one.
Improper Fraction
A fraction whose numerator is greater than or equal to its denominator.
Inequality
A mathematical statement comparing values using symbols like < or >.
Infinite
Without any limit or end.
Intercept
The point where a graph crosses an axis.
Intersection
The set of elements common to two or more sets.
Inverse
An operation or function that reverses the effect of another.
Irrational Number
A number that cannot be written as a simple fraction.
Isosceles Triangle
A triangle with at least two equal sides.
Least Common Multiple
The smallest multiple shared by two or more numbers.
Line
A straight path extending infinitely in both directions.
Line Segment
A part of a line with two endpoints.
Linear Equation
An equation whose graph forms a straight line.
Logarithm
The exponent needed to produce a number from a given base.
Magnitude
The size or absolute value of a quantity.
Multiple
The product of a number and an integer.
Natural Number
A positive counting number.
Negative Number
A number less than zero.
Octagon
A polygon with eight sides.
Odd Number
An integer not divisible by 2.
Origin
The point (0,0) on the coordinate plane.
Parallel Lines
Lines that never intersect because they remain the same distance apart.
Pentagon
A polygon with five sides.
Percent
A ratio expressed out of one hundred.
Perpendicular Lines
Lines that intersect to form right angles.
Plane
A flat two-dimensional surface extending infinitely in all directions.
Point
An exact location with no size or dimensions.
Polygon
A closed plane figure made of straight line segments.
Polyhedron
A three-dimensional solid with flat polygonal faces.
Positive Number
A number greater than zero.
Prime Number
A whole number greater than one with exactly two positive factors.
Prism
A solid with two parallel congruent polygonal bases.
Probability
The likelihood that an event will occur.
Product
The result of multiplication.
Proportion
An equation showing two ratios are equal.
Pyramid
A solid with a polygonal base and triangular faces meeting at one vertex.
Quadrilateral
A polygon with four sides.
Quadratic
An expression or equation involving a variable squared.
Quotient
The result of division.
Radius
The distance from the center of a circle to its edge.
Range
The complete set of possible output values of a function.
Ratio
A comparison of two quantities using division.
Ray
A part of a line with one endpoint extending infinitely in one direction.
Reciprocal
A number that, when multiplied by the original number, equals one.
Reflection
A transformation that flips a figure across a line.
Regular Polygon
A polygon with all sides and angles equal.
Rhombus
A quadrilateral with four equal sides.
Rotation
A transformation that turns a figure around a fixed point.
Scalar
A quantity having magnitude but no direction.
Secant
A line that intersects a circle at two points.
Sequence
An ordered list of numbers following a pattern.
Set
A well-defined collection of distinct objects.
Similar Figures
Figures with the same shape but not necessarily the same size.
Slope
A measure of the steepness of a line.
Sphere
A perfectly round three-dimensional object with every point equally distant from its center.
🔬 Science
Acid
A chemical substance with a pH less than 7 that can donate a hydrogen ion and typically tastes sour.
Allele
A variant or different version of a specific gene that determines a particular trait.
Atom
The basic, smallest unit of a chemical element, composed of protons, neutrons, and electrons.
Bacteria
Single-celled, microscopic organisms that lack a distinct nucleus and can be beneficial or pathogenic.
Base
A chemical substance with a pH greater than 7 that accepts hydrogen ions and typically feels slippery.
Catalyst
A substance that speeds up the rate of a chemical reaction without being consumed or altered itself.
Cell
The fundamental structural, functional, and biological unit of all living organisms.
Chromosome
A thread-like structure made of DNA and proteins found in the nucleus of a cell, carrying genetic data.
Compound
A pure substance made of two or more different chemical elements chemically bonded together.
DNA
Deoxyribonucleic acid; the molecule that carries genetic instructions for the development and functioning of living things.
Ecosystem
A community of living organisms interacting with each other and their non-living physical environment.
Electron
A tiny, subatomic particle with a negative electric charge that orbits the nucleus of an atom.
Element
A pure substance consisting entirely of atoms that all share the exact same number of protons.
Evolution
The gradual process of change in the inherited traits of a population over successive generations.
Homeostasis
The process by which a living organism maintains a stable internal environment despite external changes.
Ion
An atom or molecule that has gained or lost one or more electrons, giving it a net electric charge.
Isotope
Forms of the same chemical element that have the same number of protons but different numbers of neutrons.
Mitosis
A process of cell division where a single cell divides into two genetically identical daughter cells.
Molecule
The smallest particle of a specific compound, formed when two or more atoms are chemically joined.
Neutron
A subatomic particle located in the nucleus of an atom that carries no electrical charge.
Photosynthesis
The process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.
Proton
A subatomic particle located in the nucleus of an atom that carries a positive electrical charge.
Respiration
The cellular process by which organisms convert nutrients into usable energy, often utilizing oxygen.
Species
A specific group of living organisms that share common characteristics and are capable of interbreeding.
Valence
The combining capacity of an atom, determined by the number of electrons in its outermost shell.
Acceleration
The rate at which an object changes its velocity over a specific period of time.
Atmosphere
The layers of gases surrounding a planet, held in place by that planet's gravity.
Density
The measure of how much mass is contained within a specific unit of volume of a substance.
Energy
The quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
Force
Any push or pull exerted on an object that can cause it to change its velocity or direction.
Friction
The resisting force that occurs when the surface of one object slides or rubs past another.
Gravity
The natural attractive force that pulls objects with mass toward one another.
Inertia
The natural tendency of an object to resist any change in its current state of motion or rest.
Kinetic Energy
The energy an object possesses due to being in active motion.
Magma
Molten or semi-molten rock located beneath the Earth's surface.
Potential Energy
The stored energy an object possesses because of its position, state, or configuration.
Velocity
The speed of an object moving in a specified, particular direction.
✍️ Language & Literature
Adjective
A descriptive part of speech that modifies, describes, or quantifies a noun or pronoun.
Adverb
A word that modifies or describes a verb, adjective, or other adverb, often explaining how, when, where, or to what degree.
Alliteration
The repetition of the same consonant sound at the beginning of closely connected words.
Analogy
A detailed comparison made between two different things to highlight a point of similarity or explanation.
Antonym
A word that possesses the opposite meaning of another given word.
Conjunction
A joining word used to link phrases, clauses, or words together within a sentence (such as and, but, or).
Dialect
A regional or social variety of a language distinguished by its unique pronunciation, grammar, or vocabulary.
Etymology
The historical study of the origins of words and how their structures and meanings have evolved over time.
Euphemism
A polite, mild, or indirect word used to replace a term that sounds too harsh, blunt, or unpleasant.
Hyperbole
An intentional, extreme exaggeration used to emphasize a point rather than be taken literally.
Idiom
An established expression whose collective meaning cannot be understood from the literal definitions of its individual words.
Irony
A literary device where the intended meaning of words is the opposite of their literal meaning, or when an outcome is contrary to expectations.
Metaphor
A direct comparison between two unrelated things that states one thing is another, without using "like" or "as."
Noun
A fundamental part of speech that names a person, place, thing, or abstract idea.
Onomatopoeia
A word that phonetically mimics, imitates, or resembles the sound that it describes (such as buzz or hiss).
Oxymoron
A figure of speech that pairs two completely contradictory terms right next to each other (such as deafening silence).
Paradox
A statement that seems self-contradictory or absurd on the surface but may reveal an underlying truth upon deeper inspection.
Personification
A literary technique where human qualities, emotions, or actions are given to non-human things or ideas.
Preposition
A word that indicates spatial, temporal, or logical relationships between a noun or pronoun and other words (such as under, over, before).
Pronoun
A substitute word used in place of a noun to prevent repetitive phrasing (such as he, she, they, it).
Satire
A literary work that uses humor, irony, exaggeration, or ridicule to critique or mock human vices, folly, or social institutions.
Simile
An explicit comparison between two different things using comparative words such as "like" or "as."
Synonym
A word that has the exact same or highly similar meaning to another word in the same language.
Syntax
The structural rules that govern how words and phrases are arranged to construct grammatically proper sentences.
Verb
A fundamental word type that expresses an action, an occurrence, or a state of being.
🌍 History & Social Studies
Alliance
A formal agreement or pact made between nations or groups to cooperate for mutual benefit or defense.
Anarchy
A state of total societal disorder resulting from the complete absence or collapse of governing authority.
Archaeology
The scientific study of past human life and cultures through the excavation and analysis of artifacts and physical remains.
Autocracy
A system of governance where supreme, absolute power is concentrated in the hands of a single ruler.
Barter
An economic system of trading goods or services directly for other goods or services without using currency.
Capitalism
An economic framework where a country's trade and industries are controlled by private owners for profit, rather than by the state.
Century
A chronological unit of time equal to exactly one hundred consecutive years.
Civics
The educational study of the rights, duties, privileges, and responsibilities of citizenship in a society.
Constitution
The fundamental system of laws and principles according to which a nation or organization is governed.
Culture
The shared customs, arts, social institutions, values, and achievements of a particular group of people.
Democracy
A system of government where the supreme power is vested in the people, who rule directly or via elected representatives.
Dictator
A ruler who wields absolute, unrestricted power over a country, typically acquired and maintained through force.
Economy
The entire system of production, distribution, consumption, and exchange of goods and services within a region or country.
Geography
The comprehensive study of the physical features of the Earth, its atmospheres, and human interaction with environments.
Globalization
The accelerating integration and interdependence of national economies, cultures, and policies across the globe.
Imperialism
A policy or practice where a powerful nation extends its influence and control over weaker nations through diplomacy or military force.
Monarchy
A traditional form of government where a single hereditary ruler, such as a king or queen, serves as the head of state.
Oligarchy
A power structure where control over a country, institution, or organization is held by a small, elite group of individuals.
Republic
A form of government where power resides in the citizens who are entitled to vote, and is exercised by elected representatives.
Suffrage
The legal and political right to cast a vote in public elections.