vernacular

noun

he wrote in the vernacular and adopted a non-academic style accessible to the public:

everyday language, spoken language, colloquial speech, native speech, conversational language, common parlance, non-standard language, jargon, -speak, cant, slang, idiom, argot, patois, dialect;

regional language, local tongue, regionalism, localism, provincialism;

informal lingo, local lingo, patter, geekspeak;

rare idiolect.

▷antonyms formal language; Latin.

vernacular Oxford Dictionary of English