Originally meaning only a baby bird, this word of unknown origin overthrew 'fowl' while its own letters rearranged — a double transformation.
A warm-blooded egg-laying vertebrate animal of the class Aves, distinguished by feathers, wings, a beak, and typically the ability to fly.
The word 'bird' comes from Old English 'bridd,' which originally meant specifically a young bird or chick, not a bird in general. The general Old English term was 'fugol' (modern 'fowl'). By the 13th century, 'bird' had broadened to mean any feathered creature, while 'fowl' narrowed to mean poultry
The word 'bird' originally meant only a baby bird or chick — the general word was 'fowl.' The young overthrew the old in one of English's most complete semantic reversals, and to make things stranger, the 'r' and 'i' swapped places (metathesis) along the way: Old English 'bridd' became Middle English 'bird.'