puckish: [19] In English folklore from the late Middle Ages onward, Puck was a mischievous but essentially harmless sprite, up to all sorts of tricks (hence the coining of puckish for ‘mischievous’). But his Anglo-Saxon ancestor Pūca was a far less pleasant proposition – for this was the Devil himself. He gradually dwindled over the centuries, but a hint of his former power remained in his placatory alternative name Robin Goodfellow. It is not known whether pūca is of Germanic or Celtic origin.
puckish (adj.)
1867, from Puck + -ish. Related: Puckishly; puckishness.