Pronunciation: (rap'id), [key]
—adj., -er, -est,
1. occurring within a short time; happening speedily: rapid growth.
2. moving or acting with great speed; swift: a rapid worker.
3. characterized by speed: rapid motion.
Usually, rapids. a part of a river where the current runs very swiftly.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.