sobriquet \SO-brih-kay; -ket; so-brih-KAY; -KET\, noun:
A nickname; an assumed name; an epithet.
Example:
His thin waist and wiry structure earned him the sobriquet of "Toothpick."
Sobriquet is from the French, from Old French soubriquet, "a chuck under the chin, hence, an affront, a nickname."