In language development, what is the term for understanding when to use certain language based on social context?

The correct term for understanding when to use certain language based on social context is pragmatics. Pragmatics involves the practical aspects of using language effectively in social situations, including the appropriate use of tone, language style, and context-specific phrases. This can include understanding nuances such as sarcasm, politeness, and the level of formality required in different social settings.

In contrast, grammar refers to the overall structure and system of a language, including its rules. Syntax specifically deals with the arrangement of words to create meaningful sentences. Semantics focuses on the meaning of words and phrases. While grammar, syntax, and semantics all play essential roles in language comprehension and production, pragmatics specifically encompasses the social and contextual factors that influence language use.