The Collaborative International Dictionary of English v.0.48:

Suffocate \Suf"fo*cate\, a. [L. suffocatus, p. p. of suffocare
   to choke; sub under + fauces the throat. Cf. Faucal.]
   Suffocated; choked. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Suffocate \Suf"fo*cate\, v. t. [imp. & p. p. Suffocated; p.
   pr. & vb. n. Suffocating.]
   1. To choke or kill by stopping respiration; to stifle; to
      smother.
      [1913 Webster]

            Let not hemp his windpipe suffocate.  --Shak.
      [1913 Webster]

   2. To destroy; to extinguish; as, to suffocate fire.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Suffocate \Suf"fo*cate\, v. i.
   To become choked, stifled, or smothered. "A swelling
   discontent is apt to suffocate and strangle without passage."
   --collier.
   [1913 Webster]

WordNet (r) 3.0 (2006):

suffocate
    v 1: deprive of oxygen and prevent from breathing; "Othello
         smothered Desdemona with a pillow"; "The child suffocated
         herself with a plastic bag that the parents had left on the
         floor" [syn: smother, asphyxiate, suffocate]
    2: impair the respiration of or obstruct the air passage of;
       "The foul air was slowly suffocating the children" [syn:
       suffocate, stifle, asphyxiate, choke]
    3: become stultified, suppressed, or stifled; "He is suffocating
       --living at home with his aged parents in the small village"
       [syn: suffocate, choke]
    4: suppress the development, creativity, or imagination of; "His
       job suffocated him" [syn: suffocate, choke]
    5: be asphyxiated; die from lack of oxygen; "The child
       suffocated under the pillow" [syn: suffocate, stifle,
       asphyxiate]
    6: feel uncomfortable for lack of fresh air; "The room was hot
       and stuffy and we were suffocating"
    7: struggle for breath; have insufficient oxygen intake; "he
       swallowed a fishbone and gagged" [syn: gag, choke,
       strangle, suffocate]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "suffocate":
   OD, asphyxiate, bake, bar, barricade, be in heat, be killed, blaze,
   block, block up, blockade, bloom, boil, bolt, bottle up, broil,
   burke, burn, censor, chock, choke, choke off, clamp down on, close,
   close off, close tight, close up, combust, constrict, cook, cork,
   cork up, crack down on, crowd, crush, damp down, debar, dog, drown,
   extinguish, famish, flame, flame up, flare, flare up, flicker,
   flush, fry, gag, garrote, gasp, glow, hold down, incandesce, jam,
   jump on, keep down, keep under, kill, lock, muzzle, obstruct,
   occlude, pack, pant, parch, pour water on, put down, put out,
   quash, quell, quench, radiate heat, repress, roast, scald, scorch,
   seethe, shimmer with heat, shut down on, shut off, shut out,
   shut tight, silence, simmer, sit down on, sit on, smash, smolder,
   smother, smothering, smudgy, snuff out, spark, squash, squeeze,
   squeeze shut, squelch, stamp out, stanch, starve, steam, stew,
   stifle, stop the breath, stop up, strangle, strangulate, stultify,
   subdue, suffocating, suppress, sweat, swelter, throttle, toast,
   trample out, trample underfoot, voice