a part of a river where the current is very fast
"The raft struggled to stay upright as it drifted down the rapid."
a rough section of a river or stream which is difficult to navigate due to the swift and turbulent motion of the water.
"The guide warned us to stay low in our boats as we entered the rapid, where the churning whitewater threatened to sweep us off course."
"The rapid increased in height after the spring thaw."
Usage: Use this noun specifically when referring to a dangerous, fast-moving stretch in a river that hinders navigation. It describes the physical turbulence rather than just general speed.
Very swift or quick.
"The rapid rise of the sun warmed the frost-covered fields within minutes."
In plain English: Rapid means happening very quickly or moving at a fast speed.
"The rapid growth of the city surprised many people."
Rapidly.
"The news spread rapidly across the entire city within hours."
In plain English: Rapid means happening very quickly or moving at a fast speed.
"The data was processed so rapidly that we finished before lunch."
The word entered English from Middle French rapide, which itself came from the Latin rapidus. Originally meaning "swift-flowing," it was applied to describe anything moving with great speed.