Meaning

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

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

adjective being or characteristic of or appropriate to everyday language

originFrom Latin vernāculus (“domestic, indigenous, of or pertaining to home-born slaves”), from verna (“a native, a home-born slave (one born in his master's house)”).

Etymology from Wiktionary, CC BY-SA 3.0