Prime1  —adj. 1 chief, most important. 2 first-rate, excellent. 3 primary, fundamental. 4 math. A (of a number etc.) Divisible only by itself and unity (e.g. 2, 3, 5, 7, 11). B (of numbers) having no common factor but unity. —n. 1 state of the highest perfection (prime of life). 2 (prec. By the; foll. By of) the best part.  [latin primus first]