The Collaborative International Dictionary of English v.0.48:

Affix \Af"fix\, n.; pl. Affixes. [L. affixus, p. p. of
   affigere: cf. F. affixe.]
   That which is affixed; an appendage; esp. one or more letters
   or syllables added at the end of a word; a suffix; a postfix.
   [1913 Webster]