downbeat
The first beat of a bar — the strongest, most emphasised beat.
In Depth
The downbeat is beat one of any measure — the moment of greatest rhythmic weight. The term comes from conducting, where the conductor's hand moves downward on beat one. In 4/4 time, the downbeat is the strongest beat, with beat three as a secondary strong beat and beats two and four as weak beats.
The downbeat provides the listener's primary rhythmic anchor. In many genres, the bass drum or bass note falls on the downbeat, grounding the rhythm. However, not all music emphasises the downbeat equally — reggae famously de-emphasises beat one, creating its characteristic laid-back feel by stressing the offbeats instead.
In reggae, the downbeat is deliberately underplayed — the characteristic skank guitar hits on beats two and four, giving the music its relaxed, offbeat feel.