Otaku

otaku, n., ("oh tah koo") 1. (Japanese) obsessive fan. 2. (gamer/geek usage) an anime geek; one who is inordinately fond of Japanese animation. See also hentai, fanboy. [GJ1]
----
Addendum: The original Japanese translation for “otaku” is an honorific of “taku”, or home. Some translations also give it as “home guard”. Over the years, it has been corrupted into “one who stays at home”, meaning one who has no social life. The odd thing about the term otaku is that it was originally a very negative term in Japanese, a very negative form of loser. Though lessened in the years, it's still fairly negative in Japan, as the otakus are seen as yet another outsider group in a culture that is very much about the society above the individual. It was Western anime fans that, just as corrupting “nerd” and “geek” to describe themselves, took another negative term and used it among themselves until it was corrupted into a positive.