![1girl 2boys blue_eyes bomssp bread brown_eyes brown_hair dark_skin dark_skinned_male eating food glasses high_collar highres hood hoodie hunk_(voltron) lance_(voltron) looking_at_viewer multiple_boys pidge_gunderson reverse_trap short_hair sitting voltron:_legendary_defender rating:s score:4 post #3555223](/cdn_image/preview/80/d6/80d6e5b04563a12213cdd0873ce889ee.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.