noun Etymology: New Latin spicula and Latin spiculum; New Latin spicula, alteration of Latin spiculum head of a spear or arrow, diminutive of spicum, spica ear of grain 1. a slender pointed usually hard body; especially one of the minute calcareous or siliceous bodies that support the tissue of various invertebrates (as sponges) 2. a spikelike short-lived prominence appearing close to the chromosphere of the solar atmosphere • spicular adjective • spiculation noun