Fast, rapid, swift, fleet, quick, speedy, hasty, expeditious mean moving, proceeding, or acting with great celerity.
Fast and rapid are often used without distinction; but fast frequently applies to the moving object and emphasizes the way in which it covers ground, whereas rapid is apt to characterize the movement itself and often to suggest its astonishing rate of speed.
Swift suggests great rapidity, frequently coupled with ease or facility of movement.
Fleet, which is chiefly in poetic or journalistic use, connotes lightness or nimbleness as well as extreme fastness or rapidity.
Quick (see also QUICK 2 ) applies especially to something that happens promptly or occupies but little time; it suggests alacrity or celerity, especially in action, rather than velocity of movement.
Speedy, when applied to persons or their motions or activities, implies extreme quickness and often hurry or haste; when applied to things and their motion or movement, it also often suggests great velocity; in general, it is opposed to dilatory.
Hasty suggests hurry or precipitousness rather than speed and often connotes the resulting confusion, disorder, or inattention.
Expeditious adds to quick or speedy the implication of efficiency; it therefore implies the absence of waste, bungling, and undue haste.