![androgynous bandages blonde_hair blood braid dark_skin gender_request long_hair mask misowhite needle red_eyes reverse_trap sheik simple_background solo super_smash_bros. surcoat the_legend_of_zelda the_legend_of_zelda:_ocarina_of_time the_legend_of_zelda:_twilight_princess turban rating:s score:5 post #2946288](/cdn_image/preview/90/3a/903a624f62895947cc059e10b6b531f3.jpg)
Per trap, a female character who looks and may or may not act masculine. Most likely also dresses like a male, although unlike mere crossdressing the character is assumed by others to be male until demonstrated otherwise.
As a rule of thumb, if you can correctly tell the gender with complete certainty from the thumbnail alone, it's not a reverse trap.
Often indicated on Pixiv by the 男装 (Dansou lit. "Disguising oneself as a man") and 男装の麗人 (Dansou no Reijin lit. "A beautiful woman disguised as a man") tags. See also tomboy, which may overlap. pool #6118 may also overlap in some places, but is not necessarily the standard.