The Collaborative International Dictionary of English v.0.48:

Snare \Snare\, n. [AS. sneara cord, a string; akin to D. snoer,
   G. schnur, OHG. snour a cord, snarahha a noose, Dan. snare,
   Sw. & Icel. snara, Goth. sn?rj? a basket; and probably also
   to E. needle. See Needle, and cf. Snarl to entangle.]
   1. A contrivance, often consisting of a noose of cord, or the
      like, by which a bird or other animal may be entangled and
      caught; a trap; a gin.
      [1913 Webster]

   2. Hence, anything by which one is entangled and brought into
      trouble.
      [1913 Webster]

            If thou retire, the Dauphin, well appointed,
            Stands with the snares of war to tangle thee.
                                                  --Shak.
      [1913 Webster]

   3. The gut or string stretched across the lower head of a
      drum.
      [1913 Webster]

   4. (Med.) An instrument, consisting usually of a wireloop or
      noose, for removing tumors, etc., by avulsion.
      [1913 Webster]

   Snare drum, the smaller common military drum, as
      distinguished from the bass drum; -- so called because (in
      order to render it more resonant) it has stretched across
      its lower head a catgut string or strings.
      [1913 Webster]

WordNet (r) 3.0 (2006):

snare drum
    n 1: a small drum with two heads and a snare stretched across
         the lower head [syn: snare drum, snare, side drum]