"Crisp" is a tasting term usually applied to dry, light-bodied white wines that are pleasantly acidic or brisk. Drinking a crisp wine provides a sensation akin to biting into a fresh green apple - the taste is slightly tart but in a savory sort of way. The finish of a crisp wine is very clean and doesn't linger on the palate the way heavy reds do. Other tasting terms you tend to hear along with crisp are "lively," "young," and "fresh."