bum noun
1 person's bottom
VERB + BUM feel, pinch A man pinched her bum on the train so she hit him. | sit on They've been sitting on their bums all day, doing nothing.
2 lazy/useless person
ADJ. low-down, no-good | lazy | beach He dropped out of college and became a beach bum.
You can also check other dicts: bum (English, 中文解释 ), wordnet sense, Collins Definition