A small depression or cavity, especially on the surface of a structure; a small fossa.
A shallow groove, especially in the cuticle of an insect or the surface of a pollen grain or spore.
3In rugose corals: a cavity or groove where one of the primitive septa has failed to develop.
Mid 18th century. From classical Latin fossula small trench from fossa + -ula, originally after French fossette.