late 15c., "made customary, habitual, often practiced or used," past-participle adjective from accustom (v.).
Entries linking to accustomed
accustom v.
"familiarize by custom or use," early 15c., accustomen, from Old French acostumer "become accustomed; accustom, bring into use" (12c., Modern French accoutumer), from à "to" (see ad-) + verb from costume "habit, practice" (see custom (n.)). Related: Accustomed; accustoming.
unaccustomed adj.
1520s, "not customary, unfamiliar," from un- (1) "not" + past participle of accustom (v.). Meaning "not accustomed or habituated" (to) is first attested 1610s (see accustomed).