• n. 流浪漢；屁股；狂歡作樂；能力差的人；嗡嗡聲；執達員（等于bumbailiff）
• vi. 流浪；靠乞討過活；發嗡嗡聲
• vt. 乞討；閑蕩
• adj. 無價值的；劣質的；很不愉快的

擬聲詞，屁股落地的聲音。后詞義進一步貶化，指閑蕩，二流子等。

bum

bum: There are two distinct words bum in English. By far the older, ‘buttocks’, is first recorded in John de Trevisa’s translation of Ranulph Higden’s Polychronicon 1387: ‘It seemeth that his bum is out that hath that evil [piles]’. It is not clear where it comes from. The other, ‘tramp, loafer’, and its associated verb ‘spend time aimlessly’ [19], chiefly American, probably come from an earlier bummer, derived from the German verb bummeln ‘loaf around, saunter’ (familiar to English speakers from the title of Jerome K Jerome’s novel Three Men on the Bummel 1900, about a jaunt around Germany).

bum (n.1)

"buttocks," late 14c., "probably onomatop?ic, to be compared with other words of similar sound and with the general sense of 'protuberance, swelling.' " [OED]

bum (n.2)

"dissolute loafer, tramp," 1864, American English, from bummer "loafer, idle person" (1855), probably from German slang bummler "loafer," from bummeln "go slowly, waste time." Bum first appears in a German-American context, and bummer was popular in the slang of the North's army in the American Civil War (as many as 216,000 German immigrants in the ranks). Bum's rush "forcible ejection" first recorded 1910.

bum (adj.)

"of poor quality," 1859, American English, from bum (n.). Bum steer in figurative sense of "bad advice" attested from 1901.

bum (v.)

1863, "to loaf and beg," American English, a word from the Civil War, perhaps a back-formation from bummer "loafer," or from bum (n.). Meaning "to feel depressed" is from 1973, perhaps from bummer in the "bad experience" sense. Related: Bummed; bumming.

1. She went off to bum round the world with a boyfriend.

她動身和一個男友去周游世界了。

來自柯林斯例句

2. Mind if I bum a cigarette?

能給我一支煙嗎？

來自柯林斯例句

3. He knows you're getting a bum deal.

他知道你在做一筆爛生意。

來自柯林斯例句

4. John lost his job and went on the bum.

約翰失業后過著流浪生活.

來自《簡明英漢詞典》

5. A man pinched her bum on the train so she hit him.

在火車上有人捏她屁股,她打了那人.

來自《簡明英漢詞典》