A Japanese slang term synonymous with "geek" that is used to describe people who have a hobby such as video gaming, anime, model kits, D&D and many others. Outside of Japan it is used almost exclusively for hobbies related to Japan, especially anime.
It is also important to note that many people make false assumptions and stereotypes against otaku. The most common fallacies are that they have no social lives and never get laid. While these are true in some cases, they are mere stereotypes and many otaku get laid on a regular basis. Such statements can be compared with saying that ALL black people are drug dealers. (It is also important to note that many otaku choose not to use the word in describing themselves due to the negative fallacies)
Another common misconception that has led to much asshattery
is that "otaku" has a set connotation, either positive or negative. This is untrue seeing as there are both practicing otaku who can be considered exempplary citizens as well as those who will never get laid. The words connotation is purely neutral. It describes people with certain hobbies and does not pertain to positive or negative behaviour.
Why these negative fallacies are often cast upon otaku and geeks, I do not know. There are people who can name useless facts about sports and music that rival the anime trivia of any otaku who are considered healthy. Furthermore, many otaku spend less time watching anime than most Americans spend watching TV. The idea that their social lives suffer from spending too much time on anime is a pure fallacy. All people have hobbies and interests that occupy their spare time, such as sports, telivision and music. Otaku are the same except their main hobby is anime. Most still have ample time left over for a healthy social life.
james is an anime afficiando and therefore an otaku.