Rapid /(răp"ĭd)/

Rap·id

Rapid

a.
  1. Very swift or quick; moving with celerity; fast; as, a rapid stream; a rapid flight; a rapid motion.
    Ascend my chariot; guide the rapid wheels.
  2. Advancing with haste or speed; speedy in progression; in quick sequence; as, rapid growth; rapid improvement; rapid recurrence; rapid succession.
  3. Quick in execution; as, a rapid penman.

Rapid

n.
  1. The part of a river where the current moves with great swiftness, but without actual waterfall or cascade; sometimes called whitewater; -- usually used in the plural; as, the Lachine rapids in the St. Lawrence. For boaters on the river, it is a place that can be hazardous, with danger of capsizing or crashing into large rocks.
    Row, brothers, row, the stream runs fast, The rapids are near, and the daylight's past.