occurring within a short time; happening speedily

rapid growth.

moving or acting with great speed; swift

a rapid worker.

characterized by speed

rapid motion.

Usually, rapids. a part of a river where the current runs very swiftly.

adjective

languishing , leisurely , slack , slow

adjective

accelerated , active , agile , breakneck , brisk , double time , expeditious , expeditive , express , fast , fleet , fleet of foot , flying , hasty , hurried , in nothing flat , light-footed , like a house on fire , lively , mercurial , nimble , on the double * , precipitate , prompt , quick as a wink , quickened , ready , really rolling , screaming , speedy , spry , swift , wingednotes:a turbulent , rock-obstructed river area is rapid (s) and steep rapids make a cataract , quick , brief , short , abrupt , cursory , desultory , furious , kaleidoscopic , meteoric , oscillatory , phantasmagoric , superficial , winged