(often in the plural) a rough section of a river or stream which is difficult to navigate due to the swift and turbulent motion of the water.
A burst of rapid fire.
Very swift or quick.
a rapid stream
Steep, changing altitude quickly. (of a slope)
Needing only a brief exposure time. (of a lens, plate, film, etc.)
Violent, severe.
Happy.
(archaic or colloquial) Rapidly.