foremost
adj.adj. the most important or famous person or thing in a group. You use this to describe someone who is a leader in their field.
adj. occupying the most prominent or leading position; most notable or important.
She is the foremost expert on climate change.
The university is widely considered the foremost institution for medical research in the country.
As the foremost authority on Renaissance art, his endorsement of the painting's authenticity was enough to settle the debate among collectors.
From Old English formest, fyrmest (“earliest, first, most prominent”), from Proto-Germanic frumistaz, from the locative stem fur-, fr- + the superlative suffix -umistaz, stem ultimately from Proto-Indo-European pr-. The suffix -umistaz was a compound suffix, created from the rarer comparative suffix -umô (as in Old English fruma) + the regular superlative suffix -istaz (English -est); -umô in turn is from Proto-Indo-European -mHo-. Cognate with Old Frisian formest, Gothic 𐍆𐍂𐌿𐌼𐌹𐍃𐍄𐍃 (frumists). See for, first and Old English fruma for more. Partially cognate to primus, from Proto-Indo-European pr- + Latin superlative suffix -imus, from Proto-Indo-European -mHo-. A comparative former was back-formed analogically, leaving the m from *-umô in place. Later the Old English suffix complex -(u)m-est was conflated with the word most through folk etymology, so that the word is now interpreted as fore + -most.
Typically used in an attributive position before the noun it modifies.