RAPID

noun

1. (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.
2. A burst of rapid fire.

adjective

1. Very swift or quick.
2. Steep, changing altitude quickly. (of a slope)
3. Needing only a brief exposure time. (of a lens, plate, film, etc.)

adverb

1. (archaic or colloquial) Rapidly.