rapid > define

noun

• A part of a river where the current is very fast.

adjective

• Done or occurring in a brief period of time.
  • usage: "a rapid rise through the ranks"
• Characterized by speed; moving with or capable of moving with high speed.
  • usage: "a rapid movement"; "a speedy car"; "a speedy errand boy"
  • synonyms: speedy

• (a.) Quick in execution; as, a rapid penman.
• (a.) Very swift or quick; moving with celerity; fast; as, a rapid stream; a rapid flight; a rapid motion.
• (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.
• (a.) Advancing with haste or speed; speedy in progression; in quick sequence; as, rapid growth; rapid improvement; rapid recurrence; rapid succession.