1) Diction 2) Expression 3) Formulation 4) French word used in English 5) Idiom 6) Lingo 7) Manner of speaking 8) Vernacular 9) Way of speaking Found on https://www.crosswordclues.com/clue/parlance
[Noun] A particular manner of speaking or use of words, for example legal or political parlance. Example: The contract was written in legal parlance. Origin:In French the verb to talk is 'parler'.
Found on http://www.bbc.co.uk/skillswise/glossary/
Par'lance noun [ Old French , from French parler to speak. See Parley .] Conversation; discourse; talk; diction; phrase; as, in legal parlance ; in common parlance . « A hate of gossip parlance and of sway.» Tennyson. Found on http://www.encyclo.co.uk/webster/P/24