rapid

(noun): (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.
(noun): A burst of rapid fire.
(adjective): Very swift or quick.
(adjective): Steep, changing altitude quickly. (of a slope)
(adjective): Needing only a brief exposure time. (of a lens, plate, film, etc.)
(adjective): Violent, severe.
(adjective): Happy.
(adverb): (archaic or colloquial) Rapidly.