The Collaborative International Dictionary of English v.0.48:

Prong \Prong\, n. [Cf. D. prangen to pinch, press, LG. prange a
   stick, or W. procio to thrust, E. prowl, pang.]
   [1913 Webster]
   1. A sharp-pointed instrument.
      [1913 Webster]

            Prick it on a prong of iron.          --Sandys.
      [1913 Webster]

   2. The tine of a fork, or of a similar instrument; as, a fork
      of two or three prongs.
      [1913 Webster]

   3. (Zool.)
      (a) A sharp projection, as of an antler.
      (b) The fang of a tooth.
          [1913 Webster]

WordNet (r) 3.0 (2006):

prong
    n 1: a pointed projection

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "prong":
   V, affluent, bayou, billabong, branch, confluent, confluent stream,
   crotch, crutch, delta, dendritic drainage pattern, effluent, fan,
   feeder, fork, furcula, furculum, groin, inguen, offshoot,
   ramification, stem, tributary, trident, wishbone