chum1Pronunciation: /tʃʌm/ informalTranslate chum | into French | into German | into Italian | into Spanish Definition of chum noun 1a close friend: she shared the cake with her chums an old school chum 2used as a friendly or familiar form of address between men or boys:it’s your own fault, chum verb (chums, chumming, chummed) [no object] form a friendship with someone:his sister chummed up with Sally [with object] Scottish accompany (someone) somewhere:I’ll chum you down the roadOrigin: late 17th century (originally Oxford University slang, denoting a room-mate): probably short for chamber-fellow. Compare with comrade and cronychum in other Oxford dictionaries Definition of chum in the US English dictionary