In mathematics, a ternary operation is an n-ary operation with n = 3. A ternary operation on a set A takes any given three elements of A and combines them to form a single element of A.

In computer science, a ternary operator is an operator that takes three arguments.

As an example:

If F is a field, the function {\displaystyle T(a,\ b,\ c)\ =\ ab+c} {\displaystyle T(a,\ b,\ c)\ =\ ab+c} is an example of a ternary operator on F. Properties of this ternary operation have been used to define planar ternary rings in the foundations of projective geometry.

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