Definition of rapid:

• 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 swift current in a river.
• a part of a river where the current is very fast
• That part of a river where the current is more rapid than usual ( gen. in pl.).
• RAPIDNESS.
• A descent in a river less abrupt than a waterfall.
• The part of a river where the current flows rapidly. Rapids imply a considerable descent of water, but not equal to a cataract. See Rapacious.
• Rapidly.
• done or occurring in a brief period of time; " a rapid rise through the ranks"
• Very swift or quick; moving with celerity; fast; as, a rapid stream; a rapid flight; a rapid motion.
• Advancing with haste or speed; speedy in progression; in quick sequence; as, rapid growth; rapid improvement; rapid recurrence; rapid succession.
• Quick in execution; as, a rapid penman.
• 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.
• Very quick or swift; moving with speed.
• Swift; speedy.
• Very quick or swift; speedy.
• Characterised by quickness of motion or of utterance; quick; swift; expeditious.

Usage examples for rapid

1. The light garden hat was set upon her dark hair and her cheeks were flushed from rapid walking.  Kent Knowles: Quahaug by Joseph C. Lincoln

2. Number one Platoon- at the enemy in front- rapid fire!  The First Hundred Thousand by Ian Hay

3. Henri turned to the boy and sent him off with a rapid order.  The Amazing Interlude by Mary Roberts Rinehart