/bʌn; bʌn/
n
1 small round sweet cake 小而圆的甜面包或点心
*a currant bun 带葡萄乾的小圆面包. Cf 参看 roll1 2.
2 (esp woman's) hair twisted into a tight knot at the back of the head （尤指女子的）发髻
*put, wear one's hair in a bun 把头发盘成发髻.
3 (idm 习语) have a `bun in the oven (infml joc 口, 谑) be pregnant 怀孕.

n[C]
[Sense: 1-3, 5; Date: 1300-1400; Origin: Perhaps from Old French bugne 'swelling (caused by a blow), type of fritter']
[Sense: 4; Date: 1800-1900; Origin: Perhaps from Scottish Gaelic bun; BUNNY]
BrE a small round sweet cake
　a sticky bun
a small round type of bread
　a hamburger bun
bun, cheese, lettuce, tomato
if a woman has her hair in a bun, she fastens it in a small round shape at the back of her head
buns [plural]AmE informal the two round parts of a person's bottom
= buttocks
have a bun in the oven
BrE informal to be pregnant - used humorously