downbeat I. \ˈ ̷ ̷ˌ ̷ ̷\noun 1.: the downstroke of the conductor indicating the first stressed beat of a musical composition; also: any first beat : thesis 2.: an ictus or arsis : stress 3.: a decline in activity or prosperity : depressed condition II. adjective : pessimistic, gloomy, unhappy < a movie with a downbeat ending >