vernacular

Vernacular describes everyday language, including slang, that's used by the people. The vernacular is different from literary or official language: it's the way people really talk with each other, like how families talk at home.

You know how some language is fancy and formal? Vernacular is different: think of it as how friends talk when no one is listening. Vernacular language includes slang and obscenities. One of the hardest things about writing for school is getting away from the vernacular and learning to write in more formal ways that don't come as naturally. You can also say specific groups have a vernacular, meaning the unique way people in a certain region or profession speak.

Definitions of vernacular
1

n the everyday speech of the people (as distinguished from literary language)

Type of:
non-standard speech
speech that differs from the usual accepted, easily recognizable speech of native adult members of a speech community

n a characteristic language of a particular group (as among thieves)

Synonyms:
argot, cant, jargon, lingo, patois, slang
Types:
street name
slang for something (especially for an illegal drug)
rhyming slang
slang that replaces words with rhyming words or expressions and then typically omits the rhyming component
Type of:
non-standard speech
speech that differs from the usual accepted, easily recognizable speech of native adult members of a speech community

adj being or characteristic of or appropriate to everyday language

“a vernacular term”
vernacular speakers”
Synonyms:
common, vulgar
informal
used of spoken and written language