bun

The word 'bun' has a delightfully obscure and debated etymology. It likely entered Middle English from the Old French buigne, which referred to a swelling or a boil, a sense that humorously connects to the rounded shape of the bread. An alternative theory suggests a possible origin in the Gaulish bounia, meaning "a swelling," further linking the word's history to the concept of a rounded protuberance. Over centuries, the term's application narrowed from a general word for a rounded lump to specifically denote a small, soft, rounded bread, and later, by metaphorical extension, to a similarly shaped hairstyle.

This is a simplex word of uncertain origin, likely from Old French buigne meaning "a swelling, bump, or boil." Its functional role is as a complete lexical root.