obsolesce v 1: become obsolete, fall into disuse; "This word has not obsolesced, although it is rarely used"
Obsolesce \Ob`so*lesce"\, v. i. [L. obsolescere. See {Obsolescent}.] To become obsolescent. [R.] --Fitzed. Hall. [1913 Webster]
20 Moby Thesaurus words for "obsolesce": age, antiquate, be superseded, become extinct, become obsolete, date, fade, fall into disuse, fossilize, fust, go out, grow old, lose currency, molder, obsolete, outdate, pass away, perish, rust, superannuate