Webster's Revised Unabridged Dictionary · 1913

Obsolete

Obsolete , adjective

[Latin obsoletus, past participle of obsolescere. See Obsolescent.]

1.
No longer in use; gone into disuse; disused; neglected; as, an obsolete word; an obsolete statute; -- applied chiefly to words, writings, or observances.
2.
(Biology) Not very distinct; obscure; rudimental; imperfectly developed; abortive.

Obsolete , intransitive verb

To become obsolete; to go out of use. [Rare] — Fitzed. Hall