bun
bun /bʌn/
noun [countable]
Origin: Perhaps from Old French bugne 'swelling (caused by a blow), type of fritter'1. British English a small round sweet cake:
a sticky bun
2. a small round type of bread:
a hamburger bun
3.
if a woman has her hair in a bun, she fastens it in a small round shape at the back of her head
4. buns [plural] American English informal the two round parts of a person’s bottom
SYN buttocks
5. have a bun in the oven British English informal to be pregnant – used humorously
bun /bʌn/
noun [countable] Sense 1-3, 5
Date: 1300-1400Origin: Perhaps from Old French bugne 'swelling (caused by a blow), type of fritter'
2. a small round type of bread:
3.

if a woman has her hair in a bun, she fastens it in a small round shape at the back of her head
4. buns [plural] American English informal the two round parts of a person’s bottom
SYN buttocks
5. have a bun in the oven British English informal to be pregnant – used humorously