Don't call erotic 2D images "Hentai"! Don't call anything besides 変態 and 変体 "Hentai"!!!
https://en.wikipedia.org/wiki/Hentai?oldid=493630044&useskin=vector this is a version from 2012
Hentai (変態 or へんたい) is a Japanese word that, in the West, is used when referring to sexually explicit or pornographic comics and animation, particularly those of Japanese origin such as anime, manga, and eroge.
The wording is since changed and they don't mention it being a western term anymore...