Definition of "spicule"

spicule

noun
plural spicules
1. A sharp, needle-like piece.
2. A tiny glass flake formed during the manufacture of glass vials
3. (biology) Any of many needle-like crystalline structures that provide skeletal support in marine invertebrates like sponges.
  Quotations
  Tear it up, and put a fragment under the microscope, and, wonder of wonders! see the maze of geometric forms exhibited in the bones of the creature; for who can help regarding the spicules as bones, even though a sponge be invertebrate?
  1860, Recreative Science, page 110
4. A needle-like mating structure found only in male nematodes.
5. (astronomy) A jet of matter ejected from the photosphere of the sun.
6. A small spike of flowers.