This document discusses stylistic differentiation in English vocabulary with respect to functional styles. It notes that vocabulary can be categorized as bookish/literary, colloquial, or neutral. Colloquial vocabulary is typical of informal oral communication and may include emotionally colored words or connotations. The document provides examples to illustrate these categories and discusses features of colloquial style such as informal phrases, grammatical variations, and broad word meanings. It also discusses terms, professionalisms, slang, and the different styles of formal English.