The Collaborative International Dictionary of English v.0.48:

Acicular \A*cic"u*lar\, a.
   Needle-shaped; slender like a needle or bristle, as some
   leaves or crystals; also, having sharp points like needles.
   [1913 Webster] A*cic"u*lar*ly, adv..
   [1913 Webster] Aciculate