stylistic variation

In linguistics stylistic variation or register is one of the many styles or varieties of language determined by such factors as social occasion, context, purpose, and audience. More generally, the term register refers to degrees of formality in language use. Style is also seen as a mark of character – Le style est l’homme même- by the Count de Buffon

principles of Linguistic Change, Volume 2: Social Factors – William Labov 2001

Principles of Linguistic Change, Volume 3 Cognitive and Cultural Factors – William Labov 2001