fast
Firmly or securely fixed in place; stable.
Word facts
Definition of Fast
Firm against attack; fortified by nature or art; impregnable; strong.
Example sentences
That rope is dangerously loose. Make it fast!
I am going to buy a fast car.
Using Fast well
A closer look at how fast is used — meaning in plain English, how close synonyms differ, and examples at different levels.
Moving or able to move at high speed; also, firmly fixed in place.
Use it for speed in most everyday contexts — it is plainer and more versatile than 'rapid' or 'swift'. Remember the second sense (firmly fixed) survives in phrases like 'hold fast' and 'fast asleep'.
Everyday speech about speed, sports, traffic, and technology; set phrases ('fast food', 'fast asleep', 'hold fast'); and the unrelated verb/noun meaning to go without food.
'Fast' as an adverb needs no '-ly' ('run fast', not 'run fastly'). Also note the two clashing senses: 'fast' can mean speedy, yet 'hold fast' and 'stuck fast' mean firmly still.
- quick
- stresses short duration or promptness more than sustained high speed
- rapid
- more formal; suits processes and rates ('rapid growth') better than casual speech
- swift
- literary and graceful — implies smooth, effortless speed
- speedy
- lighter and more informal, often about a quick result ('a speedy recovery')
- brisk
- means lively and energetic rather than truly fast ('a brisk walk')
- slow
- the plain, direct opposite for speed
- sluggish
- stronger and negative — slow in a heavy, lethargic way
- loose
- opposite of the 'firmly fixed' sense, as in 'come loose' vs 'hold fast'
- Beginner That car is very fast.
- In writing The startup grew fast, but its foundations were held fast by a careful, patient team.
- Advanced Rumour travels fast; the truth, held fast by facts, always seems to arrive a step behind.
The odd 'fixed' sense hides in 'fast asleep' — so deeply held in sleep you can't easily be moved.
Synonyms for Fast
Related words
Words closely connected to Fast in meaning or use:
Words that rhyme with Fast
Try Fast in the word tools
Browse words near Fast
Explore more words that start with the letter F in Word Explorer, or use the A-Z browser to discover other vocabulary starting from any letter.
FAQ
Questions people ask
What does fast mean?
Firmly or securely fixed in place; stable. It is an adjective.
How many syllables does fast have?
Fast is a one-syllable word, said in a single beat: fast.
What part of speech is fast?
In a sentence, fast functions as an adjective. As a noun, it names a thing, idea, or concept.
What are synonyms for fast?
Close in meaning to fast are profligate, prompt, libertine, hot — choose the one whose tone fits your sentence.
How do you use fast in a sentence?
Example: "That rope is dangerously loose. Make it fast!"