What does 'fast' mean and the differences between the words 'fast, rapid, quick, swift, speedy, high-speed, hasty'.

The meanings of the words fast, rapid, quick, swift, speedy, high-speed, hasty are similar. However, there are small differences between them.

fast

It denotes something that moves fast or can move fast. It is often used especially in spoken language.

・a fast car/animal/runner

・The internet connection is very fast at the library.

・The cheetah is known for its ability to run incredibly fast.

rapid 

It is used to indicate something that happens in a short time, especially when talking about a change, growth or development.

・a rapid change/progress/growth

・The construction project progressed at a rapid pace.

・The company experienced rapid growth in the past year.

quick

It is used to indicate something done in a short time.

・a quick reply/glance/shower

・The student provided a quick answer to the teacher's question.

swift

It is used to indicate something that is done quickly without delay.

・a swift response/action

・His swift reflexes saved him from colliding with the oncoming car.

speedy

It is used to indicate something that moves or happens quickly. It usually has a positive meaning, emphasizing the efficiency of something and that it is done smoothly and quickly.

・a speedy resolution/recovery/delivery

・He provided a speedy resolution to the issue.

high-speed

It is used to refer to something that is designed to work or move quickly.

・a high-speed train

・High-speed internet is essential for my work.

hasty

It indicates that something is done too quickly without enough thought.

・He made a hasty decision and regretted it later.