parlance(n = noun.communication) idiom - a manner of speaking that is natural to native speakers of a language;
is a kind of expression, formulation

   Conversation; discourse; talk; diction; phrase; as, in legal parlance; in common parlance. [1913 Webster]
"A hate of gossip parlance and of sway." [1913 Webster]

parlance, n. a particular way of speaking, esp. as regards choice of words, idiom, etc.

Etymology:
OF f. parler speak, ult. f. L parabola (see PARABLE): in LL = 'speech'

N  speech, faculty of speech, locution, talk, parlance, verbal intercourse, prolation, oral communication, word of mouth, parole, palaver, prattle, effusion, oration, recitation, delivery, say, speech, lecture, harangue, sermon, tirade, formal speech, peroration, speechifying, soliloquy, allocution, conversation, salutatory : screed: valedictory, oratory, elocution, eloquence, rhetoric, declamation, grandiloquence, multiloquence, burst of eloquence, facundity, flow of words, command of words, command of language, copia verborum, power of speech, gift of the gab, usus loquendi, speaker, spokesman, prolocutor, interlocutor, mouthpiece, Hermes, orator, oratrix, oratress, Demosthenes, Cicero, rhetorician, stump orator, platform orator, speechmaker, patterer, improvisatore, speaking, spoken, oral, lingual, phonetic, not written, unwritten, outspoken, eloquent, elocutionary, oratorical, rhetorical, declamatory, grandiloquent, talkative, Ciceronian, nuncupative, Tullian, orally, by word of mouth, viva voce, from the lips of, quoth he, said he, action is eloquence, pour the full tide of eloquence along, she speaks poignards and every word stabs, speech is but broken light upon the depth of the u, to try thy eloquence now 'tis time.