RAPID

I. adjective Etymology: Latin ~us seizing, sweeping, ~, from rapere to seize, sweep away; akin to Lithuanian aprėpti to embrace Date: 1634 marked by a fast rate of motion, activity, succession, or occurrence, see: fast ~ly adverb ~ness noun II. noun Date: 1765 a part of a river where the current is fast and the surface is usually broken by obstructions