Cock-a-Hoop

Recorded since the mid-1500s, and widely regarded by etymologists as one of the most tangled word histories in English. The Oxford English Dictionary traces it to an older phrase, "to set cock a hoop," of genuinely unknown meaning, possibly describing the action of opening a tap to let drink flow freely at a celebration. A 17th-century writer guessed that "cock" referred to a barrel's spigot; others have suggested "hoop" comes from the French word for a cockerel's crest, tying the phrase to a triumphantly crowing rooster instead. A later spelling, "cock-a-whoop," muddied the waters further by suggesting the rooster theory even more strongly, without actually proving it. After several centuries of effort, etymologists have simply never landed on one satisfying answer.