chum
noun/tʃʌm/
/tʃʌm/
(old-fashioned, informal)- a friend
朋友；伙伴 - an old school chum
老校友
Word Originlate 17th cent. (originally Oxford University slang, denoting a room-mate): probably short for chamber-fellow. Compare with comrade and crony. - an old school chum