Words related to fast

faster (n.)
"one who fasts," c. 1300, agent noun from fast (v.).
avast (interj.)

1680s, a nautical interjection, "hold! stop!" probably worn down from Dutch houd vast "hold fast." See hold (v.) + fast (adv.).

AVAST. — The order to stop, or pause, in any exercise or operation; as Avast heaving — that is to say, desist, or stop, from drawing in the cable or hawser, by means of the capstan &c. [George Biddlecombe, "The Art of Rigging," 1848]
bedfast (adj.)
"bedridden," 1630s, from bed (n.) + fast (adj.).
fasten (v.)
Old English fæstnian "make fast, make firm, fix, secure," also "ratify, betroth, confirm," from Proto-Germanic *fastinon "to make firm or fast" (source also of Old Frisian festnia "to make firm, bind fast," Old Saxon fastnon, Old High German fastnion, German festnen, Old Norse fastna "to pledge, betroth"), from PIE *fast "solid, firm" (see fast (adj.)). Related: Fastened; fastening.
fastly (adv.)
"quickly," c. 1200, former adverbial cousin to fast (adj.), from Old English fæstlic "firmly, fixedly, steadfastly, resolutely;" obsolete in 19c., simple fast taking its place.
fastness (n.)
"a place not easily forced, a stronghold," late Old English fæstnes "firmness, strongness, massiveness, stability; the firmament," from fast (adj.) in its older sense of "firm, fixed in place" + -ness.
handfast (v.)

"betroth (two people), bind in wedlock; pledge oneself to," early 12c., from Old English handfæsten and cognate Old Norse handfesta "to pledge, betroth; strike a bargain by shaking hands;" for first element see hand (n.); second element is from Proto-Germanic causative verb *fastjan "to make firm," from PIE *past- "solid, firm" (see fast (adj.)). Related: Handfasted; handfasting. The noun in Old English was handfæstung.

shamefaced (adj.)

"modest, bashful," 1550s, folk etymology alteration of shamefast, from Old English scamfæst "bashful," literally "restrained by shame," or else "firm in modesty," from shame (n.) + -fæst, adjectival suffix (see fast (adj.)). Related: Shamefacedly; shamefacedness.

shamefaced, -fast. It is true that the second is the original form, that -faced is due to a mistake, & that the notion attached to the word is necessarily affected in some slight degree by the change. But those who, in the flush of this discovery, would revert to -fast in ordinary use are rightly rewarded with the name of pedants .... [Fowler]
soothfast (adj.)

"truthful," Old English soðfæst "true, trustworthy, honest, just, righteous;" see sooth (n.) + fast (adj). Related: Old English soðfæstnes "truthfulness, fairness, fidelity;" soðfæstlic "true, sincere;" soðfæstlice "truly, honestly."

steadfast (adj.)
Old English stedefæst "secure in position, steady, firm in its place," from stede (see stead) + fæst (see fast (adj.)); similar formation in Middle Low German stedevast, Old Norse staðfastr "steadfast, firm; faithful, staunch, firm in one's mind." Of persons, in English, "unshakable, stubborn, resolute" from c. 1200. Related: Steadfastly, steadfastness.