The Collaborative International Dictionary of English v.0.48:

Perish \Per"ish\, v. t.
   To cause perish. [Obs.] --Bacon.
   [1913 Webster]

   perish the thought I hope it will never happen; -- a phrase
      used after mention of a possible undesirable event,
      sometimes facetiously.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Perish \Per"ish\, v. i. [imp. & p. p. Perished; p. pr. & vb.
   n. Perishing.] [OE. perissen, perisshen, F. p['e]rir, p.
   pr. p['e]rissant, L. perire to go or run through, come to
   nothing, perish; per through + ire to go. Cf. Issue, and
   see -ish.]
   To be destroyed; to pass away; to become nothing; to be lost;
   to die; hence, to wither; to waste away.
   [1913 Webster]

         I perish with hunger!                    --Luke xv. 17.
   [1913 Webster]

         Grow up and perish, as the summer fly.   --Milton.
   [1913 Webster]

         The thoughts of a soul that perish in thinking.
                                                  --Locke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

perish
    v 1: pass from physical life and lose all bodily attributes and
         functions necessary to sustain life; "She died from
         cancer"; "The children perished in the fire"; "The patient
         went peacefully"; "The old guy kicked the bucket at the age
         of 102" [syn: die, decease, perish, go, exit,
         pass away, expire, pass, kick the bucket, cash in
         one's chips, buy the farm, conk, give-up the ghost,
         drop dead, pop off, choke, croak, snuff it] [ant:
         be born]

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "perish":
   age, antiquate, be annihilated, be consumed, be destroyed,
   be done for, be gone, be killed, be lost, be no more, be wiped out,
   become extinct, become obsolete, break down, cease, cease to be,
   cease to exist, cease to live, collapse, come to naught,
   come to nothing, conk out, corrupt, croak, crumble, date, decay,
   decease, decline, decompose, dematerialize, demise, depart,
   depart this life, die, die away, die out, disappear, disintegrate,
   dispel, disperse, dissipate, dissolve, do a fade-out, dwindle, end,
   erode, evanesce, evaporate, exit, expire, fade, fade away,
   fade out, fall, fall asleep, flee, fly, fossilize, fust, go,
   go away, go out, go under, grow old, hide, leave no trace,
   leave the scene, lose currency, melt, melt away, molder, obsolesce,
   outdate, part, pass, pass away, pass on, pass out, pass over,
   peg out, peter out, put off mortality, putrefy, quit this world,
   retire from sight, return to dust, rot, run out, rust, sink,
   sink away, spoil, stop breathing, succumb, suffer an eclipse,
   superannuate, turn, up and die, vanish, vanish from sight, waste,
   waste away, wear away, yield the ghost