best

Best has 1 syllable.

noun. Canadian physiologist (born in the United States) who assisted F. G. Banting in research leading to the discovery of insulin (1899-1978).

adjective. (comparative and superlative of `well') wiser or more advantageous and hence advisable.

adverb. From a position of superiority or authority.

noun. The person who is most outstanding or excellent; someone who tops all others.