“Fast” is a hard-working word. It does duty as a noun, a verb, an adjective and an adverb. Let’s have a closer look…
As an adjective Probably its most common usage, relating to speed. That’s a fast car. He’s a fast driver. Can also be used in relation to time: My watch is five minutes fast (showing five minutes later than the real time).
As an adverb He drives too fast. Her heart was beating fast. Also used in the sense of firmly or securely: The window was stuck fast and I couldn’t open it. The wheels were stuck fast in the mud.
As a verb In a completely different sense, “fast” can also be used to mean not eating, or eating very little. Muslims fast during the month of Ramadan. The patient is required to fast before surgery.
As a noun A fast is a period of not eating. How to break a fast safely. This is the origin of the English word breakfast, the meal when people break their overnight fast.
Many phrases and idioms use the word fast, and not all are obvious. A person who is fast asleep is sleeping deeply and probably won’t wake up easily. If you play fast and loose with someone, you are acting irresponsibly and being insincere: She’s playing fast and loose with his affections. Fast and furious describes a game or show where the events are lively and full of action. And somebody who stands or holds fast refuses to change their mind. She always held fast to her principles.