fleur-de-lis

From earlier flower-de-luce ("flower of light" by association with Latin lucem), from Middle English flourdelis, flour delice (literally “flower of joy, lovely flower”) (whence Anglo-Latin flos deliciae), from Anglo-Norman flour de lis (“lily flower”); the modern English form was remodelled after modern French fleur de lis (“lily flower”).

There is some uncertainty as to whether the symbol was originally meant to be a lily or an iris, the head of a sceptre, or something else, and thus whether the etymology of the term is straightforward (fleur (“flower”), de (“of”), lis (“lily”)) or not (other suggestions include fleur de Lys, "flower of the Lys river").