オタク

Etymology
From, the honorific version of , referring to 1982–1983  fans, or perhaps earlier; see.

Noun

 * 1)  geek, nerd, freak, no-lifer; one who is obsessed with something to the exclusion of such things as social interaction.

Usage notes

 * Unlike in English, where the word is used to refer to fans of anime and manga specifically, this term can be used to denote people with a heavy interest in any other topic, theme or hobby.
 * The term has recently gained derogatory connotations in its mainstream usage, whereas its non-derogatory usage continues mostly in its shortened forms and  (see,  (tetsuota, "railway fan")).