Other forms: buns
A bun is hair wound into a tight ball at the back of the head. Wear her hair in a bun, a messy bun, pin the bun.
It is the standard for ballet and for many kitchens and hospitals, because it keeps hair completely out of the way. The other sense is the small round bread, and the hair sense came from the shape. Note bun in the oven, meaning pregnant.
Middle English bunne means a small cake, from Old French bugne, a swelling or fritter. The hair sense came from the shape.
Proto-Indo-European
*bʰenǵʰ- — thick, dense, fat
Proto-Germanic
*bungô
Frankish
*bungjo — little clump
Old French
bugne
Anglo-Norman
bugne — bump on the head; fritter
Middle English
bunne — wheat cake, bun
English, today
bun
Built from
From Middle English bunne (“wheat cake, bun”), from Anglo-Norman bugne (“bump on the head; fritter”), from Old French bugne (hence French beignet), from Frankish bungjo (“little clump”), diminutive of bungu (“lump, clump”), from Proto-Germanic bungô, bunkô (“clump, lump, heap, crowd”), from Proto-Indo-European bʰenǵʰ- (“thick, dense, fat”). Cognate with Dutch bonk (“clump, clot, cluster of fruits”). More at bunch.
Etymology from Wiktionary, CC BY-SA