S / serrācŭlum
noun

serrācŭlum

gen. serrācŭli · gender neuter · decl. 2nd
a steering-oar; rudder
a steering-oar, rudder: πηδάλιον, clavus navis, Gloss. Philox.; Dig. 9, 2, 29, § 2 dub. (others, servaculum or feraculum).