Someone who likes anime. Probably like you, whoever's reading this.
e.g., Rayne, you like anime... So you must be an otaku right?
A person who is obsessed in anime and manga and appreciates the people who are not interested in particular anime or manga in general unlike the WEEABOO. Otaku is not referring to British or European. Otaku are only Asians or Japanese who watch Anime and read manga a lot
I am an otaku and happily recommend some good anime to watch for my friend.