affix (v.) Look up affix at
"fasten, join, attach," 1530s, from Medieval Latin affixare, frequentative of Latin affigere (past participle affixus) "fasten to, attach," from ad "to" (see ad-) + figere "fasten" (see fix (v.)).

According to OED first used by Scottish writers and thus perhaps the immediate source was Middle French affixer, a temporarily re-Latinized spelling of Old French afichier (Modern French afficher), from a Medieval Latin variant of the Latin verb. The older form in English was affitch (Middle English afficchen, late 14c.), from Old French afichier. Related: Affixed; affixt; affixing.
affix (n.) Look up affix at
"that which is joined or attached," 1610s, from affix (v.) or from French affixe, noun use of the adjective from the verb in French. Related: Affixal.