'downbeat' originates from the combination of 'down' and 'beat', where 'down' refers to the direction of the conductor's baton and 'beat' refers to the musical rhythm.

'downbeat' was used in the context of music to describe the first beat of a measure, and later adopted a metaphorical meaning in language.

Initially, it meant 'the first beat in a measure', but over time it evolved to also mean 'pessimistic or negative' in a broader context.