1620s, a type of coagulated food, from Welsh llymru "sour oatmeal jelly boiled with the husks," of uncertain origin. Later of a sweet dish in cookery (1747). Figurative use, of flattery, empty talk, is from 1740s.
fluid
fluidity
fluke
fluky
flume
flummery
flummox
flung
flunk
flunky
fluonomist