Meaning of AFFINE in English

I. a-ˈfīn, ə- noun

Etymology: Anglo-French affin, from Latin affinis, from affinis related

Date: circa 1509

: a relative by marriage : in-law

II. adjective

Etymology: Latin affinis, adjective

Date: 1918

: of, relating to, or being a transformation (as a translation, a rotation, or a uniform stretching) that carries straight lines into straight lines and parallel lines into parallel lines but may alter distance between points and angles between lines

affine geometry

• af·fine·ly adverb

Merriam-Webster's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.