143 words · A to Z
Maths Dictionary
Stuck on a word in class? Find its simple meaning here, with an example and a picture.
143 words found
A
- Acute angleAn angle less than 90°: smaller than the corner of a book.
- Adjacent sideIn a right-angled triangle, the side next to the angle you are using (but not the hypotenuse).
- Algebraic expressionA group of numbers, letters and operation signs with no equals sign.
- AngleThe amount of turn between two lines that meet at a point. It is measured in degrees (°).
- Angle of depressionThe angle you look DOWN through, measured from the horizontal, to see something below you.
- Angle of elevationThe angle you look UP through, measured from the horizontal, to see something above you.
- ApproximationA value that is close to the exact value but easier to use.
- ArcPart of the curved edge (circumference) of a circle.
- AreaThe amount of flat space inside a shape. It is measured in square units such as cm2 or m2.
- Arithmetic progression (AP)A sequence where you add (or subtract) the same number each time.
- AverageOne number that represents a whole set of data. The three averages are the mean, median and mode.
- Axis (axes)One of the two number lines on a graph: the x-axis goes across, the y-axis goes up.
B
- Bar chartA chart that uses bars of different heights to show and compare amounts.
- Base (of a power)The number that is multiplied by itself in a power.
- BearingA direction given as an angle measured clockwise from North, always written with three figures.
- Binary (base 2)A number system that uses only the digits 0 and 1. Computers use it.
- BisectTo cut exactly into two equal parts.
C
- ChordA straight line joining two points on the edge of a circle.
- CircumferenceThe distance all the way round a circle: its perimeter.
- CoefficientThe number in front of a letter in a term. It tells you how many of that letter there are.
- Common differenceThe fixed amount added each time in an arithmetic progression.
- Common ratioThe fixed number you multiply by each time in a geometric progression.
- Compound interestInterest that is added to your money each year, so next year you earn interest on the interest too.
- CongruentExactly the same shape AND the same size.
- ConstantA value that does not change: a number on its own.
- CoordinatesA pair of numbers (x, y) that gives the position of a point on a graph.
- Cosine (cos)In a right-angled triangle, cos θ = adjacent ÷ hypotenuse.
- Cube numberA number multiplied by itself three times.
- Cumulative frequencyA running total of the frequencies. Its graph is an ogive.
- Cyclic quadrilateralA four-sided shape whose four corners all lie on a circle. Its opposite angles add up to 180°.
D
- DecimalA number with a decimal point, showing parts smaller than one.
- Decimal places (d.p.)The number of digits after the decimal point.
- Degree (°)The unit for measuring angles. A full turn is 360°.
- DenominatorThe bottom number of a fraction. It tells you how many equal parts the whole is cut into.
- DepreciationThe fall in value of something, like a car or machine, as it gets older.
- DerivativeThe gradient function of a curve, written dydx. It tells you how steep the curve is at every point.
- DeterminantA single number worked out from a square matrix. For abcd it is ad − bc.
- DiameterA straight line across a circle through its centre. It is twice the radius.
- DigitAny of the symbols 0 to 9 used to write numbers.
- Directed numbersNumbers with a sign (+ or −) that shows direction: above or below zero.
- DiscountAn amount taken off the price, often as a percentage.
E
- EquationA statement that two things are equal, with an equals sign. Solving it means finding the unknown.
- Equilateral triangleA triangle with all three sides equal and all three angles 60°.
- Equivalent fractionsFractions that look different but have the same value.
- Even numberA whole number that divides exactly by 2.
- EventA result, or set of results, of an experiment that you want the probability of.
- ExpandTo remove brackets by multiplying everything inside by what is outside.
- Exterior angleThe angle between one side of a shape and the next side extended outwards.
F
- FactorA whole number that divides exactly into another number, with no remainder.
- FactoriseTo write an expression as a product by putting it into brackets: the opposite of expanding.
- FractionA part of a whole, written as one number over another.
- FrequencyHow many times something happens or appears in a set of data.
G
H
I
- Improper fractionA fraction whose numerator is bigger than (or equal to) its denominator.
- Independent eventsEvents where one happening does not change the chance of the other.
- Index (power)The small raised number that says how many times to multiply the base by itself.
- InequalityA statement that one thing is bigger or smaller than another, using <, >, ≤ or ≥.
- IntegerA whole number: positive, negative or zero. No fractions or decimals.
- IntegralThe result of integration: the reverse of differentiation. A definite integral gives the area under a curve.
- Interior angleAn angle inside a shape, at one of its corners.
- Intersection (∩)The elements that are in BOTH sets: the overlap in a Venn diagram.
- Isosceles triangleA triangle with two equal sides. The two angles facing them are also equal.
L
- LCM (lowest common multiple)The smallest number that is a multiple of two or more numbers.
- Like termsTerms with exactly the same letters and powers. Only like terms can be added or subtracted.
- Locus (loci)The path traced by a point that moves according to a rule.
- Logarithm (log)The power a base must be raised to in order to give a number.
M
- Matrix (matrices)A rectangle of numbers set out in rows and columns, inside brackets.
- MeanThe total of all the values divided by how many values there are.
- MedianThe middle value when the data is arranged in order.
- Mixed numberA whole number and a fraction together.
- ModeThe value that appears most often in a set of data.
- MultipleThe result of multiplying a number by a whole number: its times table.
- Mutually exclusive eventsEvents that cannot happen at the same time.
N
O
- Obtuse angleAn angle bigger than 90° but less than 180°.
- Odd numberA whole number that leaves a remainder of 1 when divided by 2.
- OgiveThe S-shaped graph of cumulative frequency. You read the median and quartiles from it.
- Opposite sideIn a right-angled triangle, the side facing the angle you are using.
- OriginThe point (0, 0) where the x-axis and y-axis cross.
- OutcomeOne possible result of an experiment.
P
- Parallel linesLines that stay the same distance apart and never meet.
- Percentage (%)A number out of 100.
- PerimeterThe total distance all the way round the outside of a shape.
- PerpendicularAt right angles (90°) to each other.
- Perpendicular bisectorA line that cuts another line exactly in half at right angles.
- Pi (π)The number you get when you divide any circle's circumference by its diameter. It is about 3.142 or 227.
- PictogramA chart that uses small pictures to show amounts, with a key to say what each picture is worth.
- Pie chartA circle cut into slices, where each slice's angle shows a share of the whole.
- Place valueThe value a digit has because of where it is in a number.
- PolygonA flat shape with three or more straight sides.
- Prime factorA factor of a number that is also a prime number.
- Prime numberA whole number bigger than 1 with exactly two factors: 1 and itself.
- PrincipalThe amount of money first borrowed or saved, before interest.
- ProbabilityHow likely something is to happen, from 0 (impossible) to 1 (certain).
- Profit and lossProfit is how much more you sell something for than you paid. A loss is when you sell for less.
- ProportionWhen two quantities change together at the same rate.
- ProtractorA semicircular tool for measuring and drawing angles.
- Pythagoras' theoremIn a right-angled triangle, the square on the hypotenuse equals the sum of the squares on the other two sides.
Q
R
- RadiusThe distance from the centre of a circle to its edge. It is half the diameter.
- RangeThe difference between the largest and smallest values: a measure of spread.
- RatioA way of comparing amounts of two or more things, written with a colon.
- ReciprocalWhat you multiply a number by to get 1: flip the fraction upside down.
- Reflex angleAn angle bigger than 180° but less than 360°.
- Right angleAn angle of exactly 90°, a quarter turn. It is marked with a small square.
- Roots (of an equation)The values of x that make an equation true. On a graph, they are where the curve crosses the x-axis.
S
- Sample spaceThe list or table of every possible outcome of an experiment.
- SectorA 'slice' of a circle between two radii and an arc.
- SequenceA list of numbers that follow a rule.
- SetA collection of things (elements), written inside curly brackets { }.
- Significant figures (s.f.)The important digits of a number, counted from the first non-zero digit.
- Similar shapesShapes with the same angles, where one is an enlargement of the other.
- Simple interestInterest paid only on the original amount (the principal), the same every year.
- Simplest formA fraction whose top and bottom have no common factor except 1.
- Simultaneous equationsTwo (or more) equations that are true at the same time, solved together.
- Sine (sin)In a right-angled triangle, sin θ = opposite ÷ hypotenuse.
- Square numberA number multiplied by itself.
- Square root (√)The number that, multiplied by itself, gives the number you started with.
- Standard deviationA measure of how spread out data is from the mean. A small value means the data is close together.
- Standard formA way to write very big or very small numbers as A × 10n, where A is at least 1 but less than 10.
- SubstitutionPutting numbers in place of letters to work out a value.
- SurdA square root that cannot be written as an exact whole number or fraction.
- Surface areaThe total area of all the faces of a solid shape.
T
- TallyMarks used to count as you go, grouped in fives (four lines and a line across).
- Tangent (tan)In a right-angled triangle, tan θ = opposite ÷ adjacent. (A tangent is also a line that touches a circle at one point.)
- TermOne part of an expression, separated by + or − signs. Also one number in a sequence.
- TriangleA polygon with three sides. Its angles add up to 180°.
U
V
- VariableA letter that stands for a number that can change or is unknown.
- VariationHow one quantity changes when another changes: directly (both go up) or inversely (one up, one down).
- VectorA quantity with both size (magnitude) and direction, drawn as an arrow.
- Venn diagramOverlapping circles inside a rectangle that show how sets are related.
- Vertex (vertices)A corner: a point where two or more lines or edges meet.
- VolumeThe amount of space a solid takes up, measured in cubic units such as cm3.