Math Terms StartingWith O

In this page math terms startingwith O we are going to see definitions of mathematical terms starting with the letter "O". We have listed out almost terms in math starting with O.In math also it is very important to know the meaning of many important words which are being used in the subject math.Each term is defined and examples are provided where ever it is necessary. Links are given for every words, by using this students can learn the meaning and its application more clearly.



Oblique angle

An angle that is not a right angle or multiple of a right angle. That is an angle which can be acute or obtuse.

Obtuse angle

An angle whose measure is more than 90° is called obtuse angle.

Obtuse triangle

A triangle with one obtuse angle.


A polygon with 8 sides and 8 angles.


In geometry a polygon with 8 faces are called octahedron.


Odds are an alternative way of expressing the likely hood of an event in statistics.odd number:A whole number which are not divisible by 2. Example: 1,3,5,7,... are all odd numbers.


 In statistics, Ogive curve is a graph showing the curve of cumulative distribution function.One-to-one function:A function from A to B is called one-to-one or 1-1 if whenever f(a)=f(b)then a=b.
Operation:The basic operations in math are addition, subtraction, multiplication and division.

One to one function

A function from A to B is called one-to-one or 1-1 if whenever f(a)=f(b)then a=b.


The basic operations in math are addition, subtraction, multiplication and division.

Opposite rays

Opposite rays are two rays that start from a common point and go off in the opposite directions

Opposite Transformation

A transformation that changes the orientation of the figure. Example: Reflection is an opposite transformation.

Order of operation

Sequence of number arranged either in ascending or descending array. Order of a polynomial, order of operations: rules in which the operations should be performed.

Ordered pair

Two numbers written in certain order (x,y). Usually written in parenthesis. In graph x value represent the number in the x axis and y value represent the number in the y axis. Example: (3,4) is a point whose x coordinate is 3 and y coordinate is 4.

Ordinal number

When objects are placed in order, we use ordinal numbers to tell the position of the number.


The y coordinate or vertical coordinate of an order pair


A special point usually denoted by 'O' used as a fixed point of reference in geometry. In graph where x and y axes meets, whose coordinates are (0,0).

Orthogonal circles

Two circles are said to be orthogonal circles if the tangent at their point of intersection are at right angles.

Orthocentre of the circle

It can be shown that the altitudes of a triangle are concurrent and the point of concurrence is called the orthocentre of the triangle.The orthocentre is denoted by O.


Ounce abbreviated as oz is a unit of mass equal to 1/16 pound.

Ordinal number

Ordinal numbers is a word used to describe the numerical position of objects. For example, if some students participated in a running race we can order them as, ' first, second, third, and so on'. First denotes the child who completed the race first. Second marks the child who came second and so on.

Odd number

A number which can not be divided evenly into groups of two is known as odd numbers.The number five can be divided into two groups of two and one group of one.

Example 1,3,5,7,.........

Odd man out

A sequence of numbers will be given. Among the numbers in the sequence, one particular number will be different from others either by operation or properties of numbers

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