I haven't run into the term Femboy before. Tomboys are distinguished by behavior, while we have be saying that androgynes are distinguished by their psychology. A female can go through a tomboy phase, while the androgyne is weird for life. Some behaviors reserved for tomboys, have been adopted by a wide range of girls and women: clothing associated with boys and men, sports, physical activities, a bold demeanor, and befriending boys as equals and peers. Boys and men, on the other hand, do more housework and cooking, and are more concerned with, and more willing to act to improve, their physical appearance
I found a reference in Wikipedia to an article from December, 1981, in the journal Sex Roles, titled: "Tomboys and sissies: Androgynous children?" According to the abstract: "This study had two purposes: (1) to identify potentially "androgynous" children as those labeled by their peers as "tomboys" and "sissies"; (2) to compare personality characteristics of "androgynous" children with those of peers. Subjects were 312 elementary school children in a midwestern city. Results indicate that the labels tomboy and sissy are not necessarily indicators of androgynous children, but important social behaviors are related to the labels. For males, the possibility of frustrated creativity was raised."
in the end, there seems to be an overlap, but androgyne is not a synonym for tomboy or femboy.
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