Moving, acting, or occurring with great speed. See Synonyms at fast1.(adjective)
An extremely fast-moving part of a river, caused by a steep descent in the riverbed. Often used in the plural.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "rapid" in a sentence
"Canyon, because the declivity within it is so great and the water descends with such tremendous velocity and continuity that he thought the term rapid failed to interpret the conditions."
"When a person is in the REM phase, there is a noticeable twitching movement of the eyes under closed lids (hence the term rapid eye movement), and the voluntary muscles of the body are usually paralysed."
"He also says China can no longer sacrifice the environment for what he describes as rapid and reckless development."