h₂éwis
“bird, winged creature”bird, winged
PIE word for bird. Gives Latin avis, Sanskrit viḥ. English "bird" is from a different root.
Discussion
The PIE noun *h₂éwis (bird, winged creature) derives from the root *h₂ew- (to dress, to put on — possibly extended to "to put on feathers, to be clothed in plumage"), though this etymological connection is debated. What is not debated is the word's survival across the family as a general term for birds.
Latin avis (bird) is the most productive reflex, generating the English vocabulary of flight and bird-keeping: avian (pertaining to birds), aviary (a bird enclosure), aviation (the art of flying — coined in the 19th century by analogy with avis, making every aircraft pilot an etymological bird-handler), and the surname Aves (the taxonomic class containing all birds). The word auspice (avis + specere, "bird-watching" — divination by observing the flight of birds) preserves one of Rome's most important religious practices: the augurs read the will of the gods in the movements of birds, and no major political decision was taken without consulting the auspices. English auspicious ("of good bird-signs") descends from this ritual vocabulary.
The related Latin augur (a priest who divines from bird-flight) may derive from a compound *awi-gus- ("bird-observer"), though the precise formation is debated. From augur came English augment, inaugurate (to take office under favourable bird-signs), and august (consecrated by augury, hence venerable — and the month August, named for Augustus Caesar, the "augmented/venerable one").
Sanskrit ví- (bird) and the related véṣ- (to fly, to rush) preserve the Indo-Iranian reflex. The Vedic hymns address birds as divine messengers, a cultural role consistent with the Roman augural tradition.
Old English does not continue this specific root for "bird" — the English word bird (OE bridd, "young bird, chick") is of unknown etymology and replaced the inherited word. However, the learned Latinate borrowings (avian, aviation, auspice) reintroduced the PIE root into English through the back door of scientific and cultural vocabulary.
The augury connection gives this root a significance beyond zoology. The PIE speakers, like their Roman descendants, apparently observed bird-flight as a source of divine information. The word for bird was thus not merely a natural-history term but a religious one — the bird as messenger between the human and divine worlds.
Notes
Source of "avian", "aviary", "aviation"