Definition of new chum in US English:

new chum

noun

informal
  • 1Australian and NZ. A newly arrived immigrant; a new arrival to an area. Now chiefly historical.

  • 2Australian and NZ. A novice, newcomer, or beginner; a person inexperienced in a particular occupation, activity, etc.

adjective

informal
  • Australian and NZ. That is a newly arrived immigrant, novice, etc. Also: characteristic of such a person; raw, inexperienced, unsophisticated, amateurish.

Origin

Early 19th century (in an earlier sense). From new + chum.

Pronunciation

new chum

/ˈnjuː ˌtʃʌm/