late 14c., from Old French adherent or directly from Latin adhaerentem (nominative adhaerens), present participle of adhaerere "stick to," from ad- "to" (see ad-) + haerere "to stick" (see hesitation).[adherent etymology, adherent origin, 英语词源]
"follower, associate, supporter," early 15c., from Old French adherent or directly from Latin adhaerentem (see adherent (adj.)). Meaning "adhesive substance" is from 1912.