adjective

1. not easily moved, freed, or separated; firm, fixed, or stuck the ship was fast on the rocks
2. firmly fastened or shut make the shutters fast
3. loyal; devoted fast friends
4. that will not fade fast colors
5. rapid in movement or action; swift; quick; speedy
6. permitting or facilitating swift movement a fast highway
7. taking or lasting a short time a fast lunch
8. showing or keeping to a time in advance of a standard or scheduled time his watch is fast
9. 1. living in a reckless, wild, dissipated way a fast crowd
   2. promiscuous sexually
10. ☆ Informal glib and deceptive a fast talker
11. Slang acting, gotten, done, etc. quickly and often dishonestly out for a fast buck
12. Bacteriology resistant to dissolution or decolorization, as certain bacteria
13. Photog. adapted to or allowing very short exposure time a fast lens, fast film
14. Now Dial. complete; sound a fast sleep

Etymology: ME < OE fæst, akin to Ger fest, firm, stable < IE base *pasto-, fixed, secure > Arm hast

adverb

1. firmly; fixedly
2. thoroughly; soundly fast asleep
3. rapidly; swiftly; quickly; speedily
4. ahead of time
5. in a reckless, dissipated way; wildly
6. Old Poet., Obsolete close; near fast by the river

Etymology: ME faste < OE fæste < adj.

noun

intransitive verb

1. to abstain from all or certain foods, as in observing a holy day
2. to eat very little or nothing

Etymology: ME fasten < OE fæstan, akin to Ger fasten, Goth fastan, lit., hold fast < base of fast

noun

1. the act of fasting
2. a day or period of fasting