![1boy 1girl bad_id bad_twitter_id closed_eyes cousins gloves hat jewelry kro long_hair meleph_(xenoblade) military military_hat military_uniform neferu_(xenoblade) pauldrons reverse_trap short_hair shoulder_armor smile uniform xenoblade_(series) xenoblade_2 rating:s score:3 post #3008264](/cdn_image/preview/f0/6e/f06e99c23e79cc6cda5ae81271c5e275.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.