first adj
1 chief, foremost, head, highest, leading, pre-eminent, prime, principal, ruling
2 earliest, initial, introductory, maiden, opening, original, premier, primeval, primitive, primordial, pristine
3 basic, cardinal, elementary, fundamental, key, primary, rudimentary adv
4 at the beginning, at the outset, before all else, beforehand, firstly, initially, in the first place, to begin with, to start with n
5 as in from the first beginning (informal)
first-class
A1 or A-one (informal) ace (informal) bad (slang) bitchin' (U.S. slang) blue-chip, boffo (slang) brill (informal) brilliant, capital, champion, chillin' (U.S. slang) choice, crack (slang) cracking (Brit. informal) crucial (slang) def (slang) dope (slang) elite, excellent, exceptional, exemplary, first-rate, five-star, great, jim-dandy (slang) marvellous, matchless, mean (slang) mega (slang) outstanding, premium, prime, second to none, sovereign, superb, superlative, the dog's bollocks (taboo slang) tiptop, top, top-class, top-drawer, top-flight, top-notch (informal) topping (Brit. slang) tops (slang) twenty-four carat, very good, world-class, inferior, second-class, second-rate, shocking (informal) terrible, third-rate
first-hand
direct, straight from the horse's mouth
first-rate
admirable, A1 or A-one (informal) bitchin' (U.S. slang) bodacious (slang, chiefly U.S.) boffo (slang) brill (informal) chillin' (U.S. slang) crack (slang) cracking (Brit. informal) crucial (slang) def (slang) dope (slang) elite, excellent, exceptional, exclusive, first class, jim-dandy (slang) mean (slang) mega (slang) outstanding, prime, second to none, sovereign, superb, superlative, the dog's bollocks (taboo slang) tiptop, top, top-notch (informal) topping (Brit. slang) tops (slang) world-class