A recent post discussed nouns employed to refer to ultimate achievement. Here, you’ll find details about adjectives that describe something that is the best, highest, or most important.
Cardinal is from the Latin term cardinalis, meaning “essential” or “principal.” Chief, meaning “highest in authority” or “most important”—by way of the Anglo-French word chef, still used in French and English as the title for a professional cook in charge of a kitchen—comes from the Latin word caput, whence capital and captain as well.
Foremost, interestingly, is not a compound of fore and most; its derivation is the Old English term fyrmest or formest, meaning (and related to) “first.” (The -est ending is the same superlative suffix seen in highest, smartest, and so on; see below for a mention of superlative.)
Paramount, ultimately derived from the Latin phrase per ad montem (“to the hill”), means “superior to all others.” Preeminent, from the Latin adjective praeeminere, meaning “to be outstanding,” means “better than others” (eminent, the word without the prefix, means simply “respected” and “successful”); the root is also seen in prominent, and all three words are distantly related to mount and mountain.
Premier and primary both come from Latin primarius, meaning “excellent, of the first rank,” which in turn is derived from primus, meaning “first.” From that word we also get prime, which, among other things, means “first-rate”; the Italian and Spanish adjective primo is sometimes used in informal English to denote something excellent. Premium, distantly related, means “high” or “higher than normal”; it stems from the Latin noun praemium, meaning “reward,” which is the meaning of the noun form. (The adjectival form, which developed less than a hundred years ago, was originally applied to a better grade of butter.)
Superior, meaning “higher,” comes directly from Latin and stems ultimately from the Latin word super; supreme, from the Latin word supremus, meaning “highest,” is related. Another related word is superlative, ultimately from superlativus, meaning “exaggerated” or “extravagant.” (A superlative is also the ultimate form of an adjective, such as largest, the superlative of large; larger is the intermediate comparative form.)
Best is itself a superlative; its comparative is better, but oddly, they are intensifications not of a word beginning with be- but of good (to make up for the lack of gooder and goodest as options); the base adjective was originally bot, which survives only in the form of boot in the idiomatic phrase “to boot,” which roughly means “in addition.”