purest / purist are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
purest: (adjective) free of extraneous elements of any kind. (adjective) free from discordant qualities. (adjective) concerned with theory and data rather than practice; opposed to applied. (adjective) (used of persons or behaviors) having no faults; sinless; - Sylvia Plath. (adjective) in a state of sexual virginity.
purist: (noun) someone who insists on great precision and correctness (especially in the use of words).
purest: p·y·UH·r·ah·s·t
purist: p·y·UH·r·ih·s·t
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)