grammatical gender (the assignment of nouns to categories such as masculine, feminine and neuter). According to Aristotle, this concept was introduced by the Greek philosopher Protagoras. In 1926, Henry Watson Fowler stated that the definition of the word pertained to this grammar-related meaning: As a social role Sexologist John Money coined the term gender role, and was the first to use it in print in a scientific trade journal. In a seminal 1955 paper he defined it as "all those things that a person says or does to disclose himself or herself as having the status of boy or man, girl or woman." The modern academic sense of the word, in the context of social roles of men and women, dates at least back to 1945, and was popularized and developed by the feminist movement from the 1970s onwards (see § Feminism theory and gender studies below), which theorizes that human nature is essentially epicene and social distinctions based on sex are arbitrarily constructed. In this context, matters pertaining to this theoretical process of social construction were labelled matters of gender. The popular use of gender simply as an alternative to sex (as a biological category) is also widespread, although attempts are still made to preserve the distinction. The American Heritage Dictionary (2000) uses the following two sentences to illustrate the difference, noting that the distinction "is useful in principle, but it is by no means widely observed, and considerable variation in usage occurs at all levels." Gender identity and gender roles Gender identity refers to a personal identification with a particular gender and gender role in society. The term woman has historically been used interchangeably with reference to the female body, though more recently this usage has been viewed as controversial by some feminists. There are qualitative analyses that explore and present the representations of gender; however, feminists challenge these dominant ideologies concerning gender roles and biological sex. One's biological sex is directly tied to specific social roles and the expectations. Judith Butler considers the concept of being a woman to have more challenges, owing not only to society's viewing women as a social category but also as a felt sense of self, a culturally conditioned or constructed subjective identity. Social identity refers to the common identification with a collectivity or social category that creates a common culture among participants concerned. According to social identity theory, an important component