Rap"id (?), a. [L. rapidus, fr. rapere to seize and carry off, to snatch or hurry away; perhaps akin to Gr. ; cf. F. rapide. Cf. Harpy, Ravish.]
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.
Milton.
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.
© Webster 1913.
Rap"id, n. [Cf. F. rapide. See Rapid, a.]
The part of a river where the current moves with great swiftness, but without actual waterfall or cascade; -- usually in the plural; as, the Lachine rapids in the St. Lawrence.
<-- sometimes called
whitewater -->
Row, brothers, row the stream runs fast,
The rapids are near, and the daylight's past.
Moore.
© Webster 1913.