Femininity (also called girlishness or womanliness) is a set of attributes, behaviors, and roles generally associated with girls and women. Femininity is socially constructed, but made up of both socially-defined and biologically-created factors. This makes it distinct from the definition of the biological female sex, as both males and females can exhibit feminine traits. Traits traditionally cited as feminine include gentleness, empathy, humility, and sensitivity, though traits associated with femininity vary depending on location and context, and are influenced by a variety of social and cultural factors. Tara Williams has suggested that modern notions of femininity in English speaking society began during the English medieval period at the time of the bubonic plague in the 1300s. Women in the Early Middle Ages were referred to simply within their traditional roles of maiden, wife, or widow.:4 After the Black Death in England wiped out approximately half the population, traditional gender roles of wife and mother changed, and opportunities opened up for women in society. Prudence Allen has traced how the concept of 'woman' changed during this period. The words femininity and womanhood are first recorded in Chaucer around 1380. In 1949, French intellectual Simone de Beauvoir wrote that 'no biological, psychological or economic fate determines the figure that the human female presents in society' and 'one is not born, but rather becomes, a woman,' an idea that was picked up in 1959 by Canadian-American sociologist Erving Goffman and in 1990 by American philosopher Judith Butler, who theorized that gender is not fixed or inherent but is rather a socially defined set of practices and traits that have, over time, grown to become labelled as feminine or masculine. Goffman argued that women are socialized to present themselves as 'precious, ornamental and fragile, uninstructed in and ill-suited for anything requiring muscular exertion' and to project 'shyness, reserve and a display of frailty, fear and incompetence.' Second-wave feminists, influenced by de Beauvoir, believed that although biological differences between females and males were innate, the concepts of femininity and masculinity had been culturally constructed, with traits such as passivity and tenderness assigned to women and aggression and intelligence assigned to men. Girls, second-wave feminists said, were then socialized with toys, games, television and school into conforming to feminine values and behaviours. In her significant 1963 book The Feminine Mystique, American feminist Betty Friedan wrote that the key to women's subjugation lay in the social construction of femininity as childlike, passive and dependent, and called for a 'drastic reshaping of the cultural image of femininity.' While the defining characteristics of femininity are not universally identical, some patterns exist: gentleness, empathy, sensitivity, caring, sweetness, compassion, tolerance, nurturance, deference, and succorance are traits that have traditionally been cited as feminine. Femininity is sometimes linked with sexual objectification and sexual appeal. Sexual passiveness, or sexual receptivity, is sometimes considered feminine while sexual assertiveness and sexual desire is sometimes considered masculine. People who exhibit a combination of both masculine and feminine characteristics are considered androgynous, and feminist philosophers have argued that gender ambiguity may blur gender classification. Modern conceptualizations of femininity also rely not just upon social constructions, but upon the individualized choices made by women.