Source : Webster's Revised Unabridged Dictionary (1913)

Extinct \Ex*tinct"\, a. [L. extinctus, exstinctus, p. p. of
   extinguere, exstinguere. See {Extinguish}.]
   1. Extinguished; put out; quenched; as, a fire, a light, or a
      lamp, is extinct; an extinct volcano.

            Light, the prime work of God, to me is extinct.
                                                  --Milton.

   2. Without a survivor; without force; dead; as, a family
      becomes extinct; an extinct feud or law.

Extinct \Ex*tinct"\, v. t.
   To cause to be extinct. [Obs.] --Shak.

Source : WordNet®

extinct
     adj 1: no longer in existence; lost or especially having died out
            leaving no living representatives; "an extinct species
            of fish"; "an extinct royal family"; "extinct laws and
            customs" [syn: {nonextant}] [ant: {extant}]
     2: of e.g. volcanos; permanently inactive; "an extinct volcano"
        [syn: {inactive}] [ant: {active}, {dormant}]
     3: of a fire; being out or having grown cold; "threw his
        extinct cigarette into the stream";  "the fire is out"
        [syn: {out(p)}]