Both meanings can be distinguished in context easily.In Japanese, the term describes any type of perverse or bizarre sexual desire or act; it does not represent a genre of work.It was Nakamura Kokyo's journal Abnormal Psychology which started the popular sexology boom in Japan which would see the rise of other popular journals like Sexuality and Human Nature, Sex Research and Sex.Originally, Tanaka Kogai wrote articles for Abnormal Psychology, but it would be Tanaka's own journal Modern Sexuality which would become one of the most popular sources of scholarly information about erotic and neurotic expression.
Weather Report Girl is considered yuri hentai in English usage for its depiction of lesbian sex, but in Japan it is just yuri.
Two early works escape being defined as hentai, but contain erotic themes.
This is likely due to the obscurity and unfamiliarity of the works, arriving in America and fading from public focus a full twenty years before importation and surging interests coined the Americanized term of hentai.
The definition clash also appears with the Japanese definition of yuri as any lesbian relationship, as opposed to its sexually explicit definition in English usage.
, and the English initialism AV (for "adult video").