Subject may refer to: An area of interest, also called a "topic". See Lists of topics and Lists of basic topics. An area of knowledge The focus of a field of study The focus of a course of study or of a class at school subject (grammar), one of two main constituents of a sentence subject case, grammatical case for a noun (nominative case) subject (philosophy), being which has experiences or a relationship with another entity or "object" research subject, organism (human or otherwise) that'… (More on Subject)