What is "downbeats"

Usage examples of "downbeats".

On the downbeats, I could just make out some bare skin over the top of the pogoing crowd.

Of course it is easiest to launch from a perch or height, but if there's no such convenience handy, all they need is a run of twenty or twenty-flve meters, enough for a couple of lifts and downbeats of the great extended wings, and then a step that doesn't touch the ground, and then they're up, aloft, soaring—maybe circling back overhead to smile and wave down at uplifted faces before arrowing off above the roofs or over the hills.