1.nounThe shield-shaped front part of an insect's head or a spider's cephalothorax."1990: Cuisinart stuck a human eyelash to his clypeus with saliva, twisted it into a handlebar mustache, and greeted citizens as they arrived at the rim of the sink. — Daniel Evan Weiss, The Roaches Have No King (Serpent's Tail 2001, p.16)"