The Collaborative International Dictionary of English v.0.48:

Proliferate \Pro*lif"er*ate\, v. t. [L. proles offspring + ferre
   to bear.]
   [1913 Webster]
   1. (Biol.) To produce or form cells; especially, to produce
      cells rapidly.
      [1913 Webster]

   2. (Zool.) To produce zooids by budding.
      [1913 Webster]

WordNet (r) 3.0 (2006):

proliferate
    v 1: grow rapidly; "Pizza parlors proliferate in this area"
    2: cause to grow or increase rapidly; "We must not proliferate
       nuclear arms"

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "proliferate":
   abound, accrue, accumulate, advance, appreciate, balloon,
   be fruitful, be productive, beget, bloat, boom, breed, breed true,
   bristle with, broaden, burgeon, copulate, crawl with, creep with,
   crescendo, crossbreed, develop, engender, exuberate, father, flow,
   fructify, gain, gain strength, generate, get, get ahead, go up,
   grow, gush, inbreed, increase, intensify, make love, mother, mount,
   multiply, mushroom, outbreed, overflow, pour, procreate, propagate,
   pullulate, rain, reproduce, reproduce in kind, rise, run over,
   run up, shoot up, shower, sire, snowball, spread, stream,
   strengthen, swarm with, swell, teem, teem with, wax, widen