c. 1300, "craving for food," from Anglo-French appetit, Old French apetit "appetite, desire, eagerness" (13c., Modern French appétit), from Latin appetitus "appetite, longing," literally "desire toward," from appetitus, past participle of appetere "to long for, desire; strive for, grasp at," from ad "to" (see ad-) + petere "go to, seek out," from PIE root *pet- "to rush, to fly."
Formerly with of or to, now with for. Of other desires or cravings, from late 14c. As an adjective, "characterized by appetite," OED and Century Dictionary list appetitious (1650s) and appetitual (1610s) as obsolete, but appetitive (1570s) continues.