Source : Webster's Revised Unabridged Dictionary (1913)

Protrude \Pro*trude"\, v. t. [imp. & p. p. {Protruded}; p. pr. &
   vb. n. {Protruding}.] [L. protrudere, protrusum; pro forward
   + trudere to thrust. See {Threat}.]
   1. To thrust forward; to drive or force along. --Locke.

   2. To thrust out, as through a narrow orifice or from
      confinement; to cause to come forth.

            When . . . Spring protrudes the bursting gems.
                                                  --Thomson.

Protrude \Pro*trude"\, v. i.
   To shoot out or forth; to be thrust forward; to extend beyond
   a limit; to project.

         The parts protrude beyond the skin.      --Bacon.

Source : WordNet®

protrude
     v 1: extend out or project in space; "His sharp nose jutted out";
          "A single rock sticks out from the cliff" [syn: {stick
          out}, {jut out}, {jut}, {project}]
     2: bulge outward; "His eyes popped" [syn: {pop}, {pop out}, {bulge},
         {bulge out}, {bug out}, {come out}]
     3: swell or protrude outwards; "His eyes bulged with surprise"
        [syn: {bulge}, {pouch}]