'downbeat' definitions:

Definition of 'downbeat'

From: WordNet
noun
The first beat of a musical measure (as the conductor's arm moves downward)

Definition of 'downbeat'

From: GCIDE
  • downbeat \downbeat\ n. (Music) the first beat of a musical measure (as the conductor's arm moves downward). [WordNet 1.5]

Synonyms of 'downbeat'

From: Moby Thesaurus