Fast vs. Rapid

 1.Fast= adjective/ adverb/ verb

####Quick/ happening quickly/ moving quickly

e.g. He is a fast bowler. [Fast= adj.]

e.g. She runs fast. [Fast= adv.]

e.g. Fast food [Fast= adj.]

e.g. Fast track [Fast= adj.]

e.g. Fast lane [Fast= adj.]

#### A period of time when you eat no food

e.g. He has fasted for three days. [Fast= verb]

#### Firmly fixed

e.g. My hand was stuck fast. [Fast= adverb]

#### If your watch or clock is fast, it shows a time that is later than the correct time.

#### If the colour of a piece of clothing is fast, the colour does not come out of the cloth when it is washed.

2.Rapid= adjective/ noun

#### Fast/ sudden/ moving quickly

e.g. The growth was rapid. [Rapid= adj.]

e.g. There has been rapid change in my school. [Rapid= adj.]

Rapid is generally used with the nouns such as growth, change, movement, response, pace etc.

#### An extremely fast-moving part of a river, caused by a steep descent in the riverbed.

[Rapid= noun]

Thank you