Bun
late Middle English: of unknown origin.
wiktionary
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.
Probably from Scots bun(“tail of a rabbit or hare”), which is probably from Scottish Gaelic bun(“bottom, butt, stump, stub”). [1]
Caribbean pronunciation of burn.
From the Revised Romanization of Korean 분(bun), from Chinese 分(“ fen”). Doublet of fen.
etymonline
bun (n.)
"small, slightly sweetened roll or biscuit," late 14c., origin obscure and much-disputed; perhaps [Skeat] from Old French buignete "a fritter," originally "a boil, a swelling," diminutive of buigne "swelling from a blow, bump on the head," from a Germanic source (compare Middle High German bunge "clod, lump"), or from Gaulish *bunia (compare Gaelic bonnach; see bannock). Spanish buñelo "a fritter" apparently is from the same source. Of hair coiled at the back of the head, first attested 1894. To have a bun in the oven "be pregnant" is from 1951.
The modern popular use of buns in the sense of "male buttocks" is from 1960s, perhaps from a perceived similarity; but bun also meant "tail of a hare" (1530s) in Scottish and northern England dialect and was transferred to human beings (and conveniently rhymed with nun in ribald ballads). This may be an entirely different word; OED points to Gaelic bun "stump, root."
