chum1

 
Pronunciation: /tʃʌm/
informal

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 road

Origin:

late 17th century (originally Oxford University slang, denoting a room-mate): probably short for chamber-fellow. Compare with comrade and crony