Fast1  —adj. 1 rapid, quick-moving. 2 capable of or intended for high speed (fast car; fast road). 3 (of a clock etc.) Ahead of the correct time. 4 (of a pitch etc.) Causing the ball to bounce quickly. 5 firm; firmly fixed or attached (fast knot; fast friendship). 6 (of a colour) not fading. 7 pleasure seeking, dissolute. 8 (of photographic film etc.) Needing only short exposure. —adv. 1 quickly; in quick succession. 2 firmly, tightly (stand fast). 3 soundly, completely (fast asleep).  pull a fast one colloq. Perpetrate deceit. [old english]