a·cic·u·la 
(ə-sĭkyə-lə)
(ə-sĭkyə-lə)n. pl. a·cic·u·lae (-lē′)
A slender, needlelike part or structure, such as a spine or bristle of certain plants and animals or a crystal of certain minerals.
[Latin, hairpin, diminutive of acus, needle; see ak- in the Appendix of Indo-European roots.]
a·cicu·late (-lĭt, -lāt′), a·cicu·lat′ed (-lā′tĭd) adj.