otaku dictionary . well it is more huge i just selected some from A,B,C ,D,G,i,i ^__^

-Ahoge: 「あほげ」[ah-ho-geh] Literally means “foolish/stupid hair.” Refers to a length of hair that sticks out from the top of the head of an anime or manga character. It is not to be confused with hair antennae.
Examples of characters with ahoge include Edward Elric from “Fullmetal Alchemist” and Konata from “Lucky Star.
-AMV: or Animated/Anime Music Video. A type of unofficial music video (fan created), to popular Anime and Music that are usually edited to sync the video clips with the chosen music or sound clips. A popular, and one of my favorite, examples would be AMV Hell.
-Aniki: big brother, usually used by thugs or gangsters.
-Anime: A style of animation developed in Japan, characterized by stylized colorful art and often adult themes.
-Arigatou: thank you
-Aishiteru: i love you
-Baba: Old woman, grandma or wise.
-Bakemono: Monster
-Baka: Idiot/Moron/Fool
-Bijin: Beautiful person (woman)
-Bishojo: Opposite of Bishonen, beautiful female heartthrob character, usually in a Shojo-genre manga.
-Bishonen: Male heartthrob character, usually in a Shojo-genre manga.
-Chibi: A big-headed, small-bodied version of a person which is general very adorable.
-Chissu/Chiwassu: Japanese slang for "Whats'up" or "Hello."
-Cosplay: Litterally meaning 'Costume-Play'. When someone dresses up as a character from an anime, manga or video game.
-Crossplay:a blend of the words crossdress and cosplay. It refers to people that dress up as characters of the opposite gender.
-Daisuki:(大好き) sort of means huge like. This is similar to Daikazoku (大家族)
This also applies to kirai(嫌い) and daikirai (ダイキライ), which is also an adjective.
-Desu: A short Japanese word that links a noun and verb, literally translated as "it is." Image boards have taken this as a meme, often repeating "desu desu desu," for various reasons, including to tease the newbies or stubbornly persist in an argument.
-Doujinshi: self-published Japanese works, usually magazines, manga or novels.
-Douitashimashite: You're welcome.
-Ecchi: Describes someone who is perverted.
-Gijinka: A Chibi-Like person who looks like an animal or creature, for example, a pokemon.
-Gomen/Gomenasai: Gomenasai and sumimasen both mean "excuse me" or "im sorry" only in a different sense. "Gomenasai" is an "excuse me I appear to have carelessly driven my car into your living room" whereas "sumimasen" is more a "could you please move out of the way so I can drive your car into living room" kind of excuse me.
-Hai: "yes" or "okay" ; Contrary to popular usage and belief, Hai does not mean "Hello" in any sense. Please stop using it as such.
-Harem: An Anime/Manga story featuring multiple girl characters and generaly a single guy character.
-Hashi: Chopsticks (it can also mean "bridge")
-Hatsune Miku/Miku:One of the first digital diva's. She is one of the original vocaliods and is arguably the most popular. She has spawned her own video game and has headlined her own concerts.
-Hentai: is a Japanese word that, in the West, is used when referring to sexually explicit or pornographic comics and animation, particularly those of Japanese origin such as anime, manga and computer games. In Japan it can be used to mean "metamorphosis" or "abnormality". The word "hentai" has a negative connotation to the Japanese and is commonly used to mean "sexually perverted".
-Itai: Painful
-Ittai: Basically saying,"What on earth?!"
-Ja ne: see you later (Can also use "Ja")