- Moving with great speed, or capable of doing so; swift, rapid. [from 14th c.]
"I am going to buy a fast car."
- Deep or sound (of sleep); fast asleep (of people). [16th-19th c.]
- (colloquial) Having an extravagant lifestyle or immoral habits. [from 18th c.]
"She's fast – she slept with him on their first date.."
- (of people) Steadfast, with unwavering feeling. (Now only in set phrases like "fast friend".) [from 10th c.]
- (computing, of a piece of hardware) Able to transfer data in a short period of time.
- (obsolete) Tenacious; retentive.
- (of photographic film) More sensitive to light than average. [from 20th c.]
- Firm against attack; fortified by nature or art; impregnable; strong.
- Causing unusual rapidity of play or action.
"a fast racket, or tennis court; a fast track; a fast billiard table"
- (of dyes or colours) Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent. [from 17th c.]
"All the washing has come out pink. That red tee-shirt was not fast."
- Ahead of the correct time or schedule. [from 19th c.]
"There must be something wrong with the hall clock. It is always fast."
- (dated) Firmly or securely fixed in place; stable. [from 9th c.]
"That rope is dangerously loose. Make it fast!"
- In a firm or secure manner, securely; in such a way as not to be moved [from 10th c.].
"Hold this rope as fast as you can."
- Quickly, with great speed; within a short time [from 13th c.].
"Do it as fast as you can."
- Immediately following in place or time; close, very near [from 13th c.].
"The horsemen came fast on our heels."
- (of sleeping) Deeply or soundly [from 13th c.].
"He is fast asleep."
- Ahead of the correct time or schedule.
"I think my watch is running fast."
- (archery) Short for "stand fast", a warning not to pass between the arrow and the target
- The period of time during which one abstains from or eats very little food.
- (Britain, rail transport) A train that calls at only some stations it passes between its origin and destination, typically just the principal stations
- The act or practice of abstaining from food or of eating very little food.
- (intransitive) To abstain from food, or eat very little, especially for religious or medical reasons.
"Muslims fast during Ramadan."