1. A spike of ice formed during the freezing of a water drop or a contained volume of water (as in a puddle or freezer container); expansion of the inward freezing ice expels any remaining water through a weak point in the shell which then freezes as a spike in the colder environment. 2. Bright spike of luminous gas extending from the chromosphere into the corona of the sun. Spicules are several hundred kilometers in diameter and extend outward 5000–10 000 km. Observed in photographs of the limb, these features have a lifetime of several minutes.