Affine

An affine algebraic group over a field k is a representable covariant functor from the category of commutative algebras over k to the category of groups such that the representing algebra is finitely generated.

Source: tatoeba (1748788)

Now, let P, Q, and R be three noncollinear points that are left fixed by an affine transformation T.

Source: wiktionary

In our example of the affine cryptosystem family, deciphering is also accomplished by an affine map, namely P#92;equiva#123;-1#125;C-a#123;-1#125;b#92;bmodN, and so the deciphering transformation uses the same algorithm as the enciphering transformation, except with a different key, namely, the pair (a#123;-1#125;,-a#123;-1#125;b).

Source: wiktionary

Clearly every linear functional is affine, and every affine function is both convex and concave.

Source: wiktionary