A·cic·u·la n.; pl. Aciculæ   Nat. Hist. One of the needlelike or bristlelike spines or prickles of some animals and plants; also, a needlelike crystal.
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  acicula
       n : a needle-like part or structure of a plant or animal or
           crystal; as a spine or bristle or crystal
       [also: aciculae (pl)]
  acicula
       See aciculum
       [also: aciculae (pl)]