per / purr 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. 👇
per: NA
purr: (noun) a low vibrating sound typical of a contented cat. (verb) indicate pleasure by purring; characteristic of cats.
per: p·ER
purr: p·ER
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)