cod (n.)
large sea fish, mid-14c. (late 13c. in a surname, Thomas cotfich), of unknown origin; despite similarity of form it has no conclusive connection to the widespread Germanic word for "bag" (represented by Old English codd, preserved in codpiece). Cod-liver oil known since at least 1610s, was recommended medicinally since 1783, but not popular as a remedy until after 1825.