bah

The word 'bah' is a natural exclamation, one of many vocalizations used to express strong negative emotion. Its origin is imitative, meant to replicate a spitting sound or a dismissive snort, conveying contempt or disgust. First recorded in English in the early 19th century, it belongs to a category of instinctive, often bilabial, interjections (like 'pooh', 'pish', or 'pshaw') that are common across languages. Its meaning is derived entirely from its sound and the conventionalized expressive force it carries in speech, rather than a compositional etymology from classical roots.

This is a simplex interjection. It is an onomatopoeic or natural exclamatory formation, not composed of smaller meaningful units (morphemes) in the modern English spelling.