n.
One of the prominent ridges or ribs extending across each of the whorls of certain univalve shells. →
n.
Anything shaped or acting like a screw; esp., a form of wheel for propelling steam vessels. It is placed at the stern, and furnished with blades having helicoidal surfaces to act against the water in the manner of a screw. See Screw propeller, below. →
n. pl.
A tribe or family of dipterous flies whose larvae live in decayed wood. Some of the tropical species are very large. →