Dictionary

Firmly or securely fixed in place; stable.

Example: That rope is dangerously loose. Make it fast!

Firm against attack; fortified by nature or art; impregnable; strong.

(of people) Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)

Moving with great speed, or capable of doing so; swift, rapid.

Example: I am going to buy a fast car.

In a firm or secure manner, securely; in such a way as not to be moved; safe, sound .

Example: Hold this rope as fast as you can.

(of sleeping) Deeply or soundly .

Example: He is fast asleep.

Immediately following in place or time; close, very near .

Example: Fast by the sturdy batsman the ball unheeded sped. / That ain't my style, said Casey. Strike one, the umpire said.

Quickly, with great speed; within a short time .

Example: Do it as fast as you can.

To restrict one’s personal consumption, generally of food, but sometimes other things, in various manners (totally, temporally, by avoiding particular items), often for religious or medical reasons.

Example: Muslims fast during Ramadan and Catholics during Lent.