Definition of Jack Jones in English:

Jack Jones

Pronunciation /ˌdʒak ˈdʒəʊnz/

adjective

slang, rare British Military
  • Alone, on one's own.

noun

slang British Military
  • Only in "on one's Jack Jones": alone, on one's own.

Origin

1920s; earliest use found in Edward Fraser (fl. 1925). From the male forename Jack + the surname Jones, rhyming slang for alone and own.