Eh is a natural interjection of uncertain date, attested from Middle English; an instinctive vocalization rather than a borrowed or derived word. In present use as an interjection, it means "used to express inquiry, surprise, or to invite agreement", keeping the historical formation close to the word's ordinary semantic work. Because the origin is uncertain, the safest account is descriptive: the attested senses can be explained, but the ultimate formation remains unresolved. This leaves the word with a compact history: its modern use is explained as a vocal reaction rather than as a borrowed or derived lexical form.