kemonomimi mode
When characters who don't normally have any animal-like features (such as ears or a tail) are depicted with animal ears, tail, and/or a little fur.
This can also include characters who are canonically animal-like, but are depicted with a different set of animal features (Danbooru post #640641, for example).
Note, however, that this does not include characters who can modally become animal-like, such as Inu Sakuya or the Strike Witches.
Also not to be confused with fake animal ears.
When there are more animal-like features like a snout or full fur use furrification instead.