(idiomatic) Used to tell someone to stop doing something. / Used other than figuratively or idiomatically: see not, so, fast.

(idiomatic) Rapid and energetic.

Alternative form of colorfast

plural of fast lane

On a multilane road, the lane intended or reserved for vehicles moving at faster speeds. / (figuratively, by extension) Any situation or activity where the pace is very rapid.

(idiomatic) In a lifestyle, employment position, or other set of circumstances where the rapid pace is exciting, frantic, or risky.

(cricket) A bowler who specialises in bowling the ball fast in cricket; as opposed to a spin bowler.

Food that is served quickly, often standardized and pre-prepared. / A type of food that is quickly made, but of low nutritional value; junk food.

(histology, of bacteria) Retaining stain when treated with an acidic solution.

(idiomatic, of rules, etc) strictly maintained