The Collaborative International Dictionary of English v.0.48:

Stifle \Sti"fle\, v. t. [imp. & p. p. Stifled; p. pr. & vb. n.
   Stifling.] [Freq. of OE. stif stiff; cf. Icel. st[imac]fla
   to dam up.]
   1. To stop the breath of by crowding something into the
      windpipe, or introducing an irrespirable substance into
      the lungs; to choke; to suffocate; to cause the death of
      by such means; as, to stifle one with smoke or dust.
      [1913 Webster]

            Stifled with kisses, a sweet death he dies.
                                                  --Dryden.
      [1913 Webster]

            I took my leave, being half stifled with the
            closeness of the room.                --Swift.
      [1913 Webster]

   2. To stop; to extinguish; to deaden; to quench; as, to
      stifle the breath; to stifle a fire or flame.
      [1913 Webster]

            Bodies . . . stifle in themselves the rays which
            they do not reflect or transmit.      --Sir I.
                                                  Newton.
      [1913 Webster]

   3. To suppress the manifestation or report of; to smother; to
      conceal from public knowledge; as, to stifle a story; to
      stifle passion.
      [1913 Webster]

            I desire only to have things fairly represented as
            they really are; no evidence smothered or stifled.
                                                  --Waterland.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stifle \Sti"fle\, n. [From Stiff.] (Far.)
   The joint next above the hock, and near the flank, in the
   hind leg of the horse and allied animals; the joint
   corresponding to the knee in man; -- called also stifle
   joint. See Illust. under Horse.
   [1913 Webster]

   Stifle bone, a small bone at the stifle joint; the patella,
      or kneepan.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stifle \Sti"fle\, v. i.
   To die by reason of obstruction of the breath, or because
   some noxious substance prevents respiration.
   [1913 Webster]

         You shall stifle in your own report.     --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stifle
    n 1: joint between the femur and tibia in a quadruped;
         corresponds to the human knee [syn: stifle, knee]
    v 1: conceal or hide; "smother a yawn"; "muffle one's anger";
         "strangle a yawn" [syn: smother, stifle, strangle,
         muffle, repress]
    2: smother or suppress; "Stifle your curiosity" [syn: stifle,
       dampen] [ant: excite, stimulate]
    3: impair the respiration of or obstruct the air passage of;
       "The foul air was slowly suffocating the children" [syn:
       suffocate, stifle, asphyxiate, choke]
    4: be asphyxiated; die from lack of oxygen; "The child
       suffocated under the pillow" [syn: suffocate, stifle,
       asphyxiate]