fouet

whip (tool); whisk; tip

From Middle French fouet, diminutive in -et of Old French fou (“beech”), from Latin fagus. Since the morpheme boundary was no longer felt in Middle French, [u.ɛ] was contracted to [wɛ] and this later developed regularly to [wa] (as it did in oi, oe). The contemporary pronunciation was reinforced by the spelling and the desire to distinguish from foi, foie and fois.