Definition of amateur hour in English:

amateur hour

noun

US
  • (On radio, television, etc.) a time slot in which amateur entertainers are invited to perform; (also in extended use) a period characterized by a lack of professionalism; an example of amateurishness or ineptitude.

adjective

US
  • Inept, shambolic, amateurish.

Origin

1920s; earliest use found in Albuquerque (New Mexico) Morning Journal.