adj. 1 quick, swift, fleet, speedy, brisk; brief, hurried, hasty, high-speed, accelerated, expeditious, rapid, express She is very fast on her feet We need a fast turn-round on this job. 2 loose, profligate, wild, extravagant, dissipated, intemperate, irresponsible, sybaritic, self-indulgent, dissolute, unrestrained, indecorous, rakish, licentious, promiscuous, immoral, wanton, lecherous, lustful They led quite a fast life till their divorce 3 firm, fastened, secure(d), fixed, tied, bound, connected, attached The boat was fast to the pier 4 firm, fixed, settled, stable, solid, immovable, unshakable or unshakeable, tight The sword was fast in the stone 5 firm, stable, steadfast, staunch, unwavering, constant, lasting, close, loyal, devoted, faithful, lasting, permanent We maintained a fast friendship over the years
adv. 6 quickly, swiftly, rapidly, speedily, briskly, presto, hastily, hurriedly, with all speed or haste, expeditiously, apace, post-haste, like a flash, in the blink of an eye, in a wink, before you can say 'Jack Robinson', in no time (at all), Colloq like a bat out of hell, like a shot, p.d.q. (='pretty damned quick'), Brit like the clappers (of hell), US and Canadian quick like a bunny or rabbit, lickety-split Don't talk so fast He ran out of there very fast. I'll be back very fast. 7 firmly, fixedly, immovably, solidly, unshakeably or unshakably, tightly, securely, soundly The rope held fast He is fast asleep. 8 closely, close to, immediately, near, (close) on, right Fast on the heels of the fugitive came the police 9 loosely, wildly, recklessly, intemperately, irresponsibly, fecklessly, extravagantly, intemperately, sybaritically, self-indulgently, dissolutely, unrestrainedly, indecorously, rakishly, licentiously, promiscuously, immorally, wantonly, lecherously, lustfully He's been living fast since inheriting that fortune