The word for a hardcore fan of something, usally anime. Most otakus know almost everything about what they like, and don't leave home due to loving that thing they go otaku for. Often people don't like being called an otaku, because to some it means that they have a very weak social life due to their fandom.
THERE IS A MASSIVE FINE LINE between OTAKU and WEEABOO. An otaku is a person that watches anime and collects stuffs thta is anime related. Otaku is actually an insult used by Japanese people in term of “House” “home” meaning that person stays in their house all day. A WEEABOO is much like a KOREABOO but obsessed with Japanese culture and thinks japan is supreme of all other countries including their own. They also used Japanese phrases mixed with English phrases like DESU and KAWAII and SUGOI
Weeaboo: OMG DEKU SAMA IS SO SUGOIIIII~~~ KYAHHHH>~<
Otaku: yeh I agree Deku is awesome but please stop that... it really is cringe