Dictionary.com
definitions

affine

[a-fahyn, uh-fahyn, af-ahyn]
noun
  1. a person related to one by marriage.
adjective Mathematics.
  1. assigning finite values to finite quantities.
  2. of or relating to a transformation that maps parallel lines to parallel lines and finite points to finite points.

Origin of affine

1500–10; < French affin related < Latin affinis akin, neighboring
Related formsaf·fine·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for affine

affine

adjective
  1. maths of, characterizing, or involving transformations which preserve collinearity, esp in classical geometry, those of translation, rotation and reflection in an axis

Word Origin for affine

C16: via French from Latin affīnis bordering on, related
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012