fast

adjective15

1. •
   quick, or able to go at a high speed

   • I am going to buy a fast car.
2. •
   Having a kinetic energy between 1 million and 20 million electron volts; often used to describe the energy state of free neutrons at the moment of their release by a nuclear fission or nuclear fusion reaction (i.e., before the neutrons have been slowed down by anything).

   • Plutonium-240 has a much higher fission cross-section for fast neutrons than for thermal neutrons.
3. •
   Able to transfer data in a short period of time.

   • But at the microlevel it consists of an unimaginable number of atoms connected by springy chemical bonds, all jiggling around at a rate that even our fastest supercomputer might envy. — 2007
4. •
   Ahead of the correct time or schedule.

   • There must be something wrong with the hall clock. It is always fast.
5. •
   Firmly or securely fixed in place; stable.

   • That rope is dangerously loose. Make it fast!
6. •
   Firm against attack; fortified by nature or art; impregnable; strong.

   • out-lawes […] lurking in woods and fast places — 1596
7. •
   Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)

   • I still hear you sayin', "Dear one, hold me fast" — 1933
8. •
   Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent.

   • All the washing has come out pink. That red tee-shirt was not fast.
9. •
   Deep or sound (of sleep); fast asleep (of people).
10. •
    Causing unusual rapidity of play or action.
11. •
    Of a place, characterised by business, hustle and bustle, etc.

    • Sydney is a fast city, and the pace is becoming increasingly more frantic. — 1968
12. •
    (old-fashioned) Having an extravagant lifestyle or immoral habits.

    • You're alone with her at last / And you're waiting 'til you think the time is right / Cause you've heard she's pretty fast / And you're hoping that she'll give you some tonight. — 1979
13. •
    (offensive, old-fashioned) Uncharacteristically mature or promiscuous for one's age.
14. •
    More sensitive to light than average.
15. •
    (no longer used) Tenacious; retentive.

    • Roses, damask and red, are fast flowers of their smells. — 1625

adverb5

1. •
   Quickly, with great speed; within a short time .

   • Do it as fast as you can.
2. •
   In a firm or secure manner, securely; in such a way as not to be moved; safe, sound .

   • Hold this rope as fast as you can.
3. •
   Ahead of the correct time or schedule.

   • I think my watch is running fast.
4. •
   Deeply or soundly .

   • The princess was sleeping fast, and her servants were fast asleep too.
5. •
   Immediately following in place or time; close, very near .

   • The horsemen came fast on our heels.
   • Fast by the sturdy batsman the ball unheeded sped. / That ain't my style, said Casey. Strike one, the umpire said.

verb3

1. •
   To practice religious abstinence, especially from food.

   • Thou didst fast and weep for the child. — 1611
2. •
   To reduce or limit one's nutrition intake for medical or health reasons, to diet.

   • The ideal would be to fast in a situation where you are not tempted by food — 1977
3. •
   To cause (a person or animal) to abstain, especially from eating.

   • At 11 weeks of age, all mice were fasted overnight and underwent gallbladder ultrasonography to determine ejection fraction. — 2007

noun3

1. •
   The act or practice of fasting, religious abstinence from food.

   • And is it not the Command of Christ, that in their Fast they should not appear unto men to fast? — 1677
2. •
   Any of the fasting periods in the liturgical year.

   • And so may we enter the Fasts at hand, beginning Lent the 30th. day of the Month Mechir — 1662
3. •
   (UK) A train that calls at only some stations it passes between its origin and destination, typically just the principal stations.

exclamation1

1. •
   Ellipsis of stand fast, a warning not to pass between the arrow and the target.

adjective1

1. •
   An acronym for remembering desirable characteristics for goal-setting: frequently discussed, ambitious, specific, transparent.

noun3

1. •
   Acronym of free advertising-supported streaming television
2. •
   Acronym of focused assessment with sonography for trauma.
3. •
   Acronym of firefighter assist and search team.

phrase1

1. •
   Acronym of facial drooping, arm weakness, speech difficulty, time, a mnemonic for diagnosing a CVA or stroke.