As per https://e621.net/wiki_pages/1588: "Feral leaning" semi-anthro characters will display human level intelligence and capacity for speech while showing generally animal behaviour, while "anthro leaning" semi-anthro characters will possibly display some superficial animal behaviours. If a semi-anthro character can realistically pass off as feral with no clothes on (and if quadruped, standing on all fours), tag feral. If not, tag anthro. If an image features both, tag both.