Aikyatchi Eyecatch. A scene or illustration used as a segue into and out of commercial breaks during a show. See Wikipedia, Everything2, or TV Tropes. And maybe also this gallery of eyecatches from Cowboy Bebop.
Animanga A type of manga that uses anime cels. It's sometimes also called cine-manga, though that might be just a term used by Tokyopop for the animanga it publishes, I'm not sure....
Anime happens to be one of my favorite substances in the universe. It generally refers to Japanese animation, though it can sometimes be used for cartoons from other countries, like France or Italy (since the animation of these countries is often similar in style to Japanese anime). Some might say the Japanese word "anime" derives from the French word "anime," which means "animation," but actually Japanese anime is just a shortened form of the English word "animation." There are different types of anime, some made for little kids, some for adults, some for pretty much anyone. It can be made for television, theaters, or OVA. See Wikipedia or Everything2. (See also Japanimation, lower this page).
Bara "Men's love." A genre about homosexual men, which is more specifically for homosexual men, as opposed to shonen ai or yaoi, which tend to be more appealing to heterosexual girls or women. See TV Tropes or Wikipedia.
BGM Background music.
Bishoujo means "beautiful girl." See Wikipedia or TV Tropes.
Bishounen means "beautiful boy." The term is often used to refer to male characters in anime or manga who look sort of feminine. See Wikipedia, Everything2, or TV Tropes.
Cabbit A cute little critter from the anime Tenchi Muyo! which turns into a space ship. See Wikipedia, or Everything2.
^_^ A basic smiley emoticon commonly used by anime/manga fans. I suppose it probably shows up in actual manga and possibly anime, too. For more anime emoticons, check out Kurt's Anime Emoticon Dictionary or Wikipedia or Everything2.
Chibi means "small," generally in a derogatory sense, as in "runt" or "shrimp." But it can also be used to describe characters in anime or manga who are drawn in a "cute," small, child-like style that isn't very realistic. Sometimes this is the permanent style of the drawings, and sometimes it is done temporarily, generally for comedic effect. When this happens, characters may be referred to as super-deformed (see lower this page). See Wikipedia.
Dattebayo has no actual meaning, but I've read that it's used as a sort of slang term in Tokyo. However, I've also read that it was made up by the creator of the manga/anime Naruto. The title character uses it to end some of his sentences, to give them extra emphasis. In the English dub, Naruto says "Believe it!" in place of "dattebayo," but this is not an entirely accurate translation (since it has no exact meaning). It could also be something along the lines of "you know?" or "don't you understand what I've said?" I'm not actually sure whether the word is used anywhere in real life, outside the context of Naruto, which is why I include it on the anime page rather than general terms. See Japan Guide.
Doujinshi are manga drawn by fans or made by small presses, based on professional anime or manga. Essentially, it's fanfic comic books. See Wikipedia, TV Tropes, or Everything2.
Ecchi Japanese way of pronouncing the letter "H," it is often used to refer to a mild form of hentai, or as a mildly derogatory term for something or someone that is perverse (usually applied to a male). See Wikipedia, TV Tropes, or Everything2.
Fan service See saabisu (lower this page).
Gaiden means "anecdote" or "supplemental biography"; in fiction such as anime or manga (or even video games), it is often used to refer to side stories (which may or may not be canonical), which expand the universe of a series (or stand-alone story), but which is not officially a part of that universe. I guess. Which makes it odd to think it may be canonical. So I dunno.... See Wikipedia or Everything2.
Gijinka See general terms page.
Global manga A term for non-Japanese manga done in the style of Japanese manga. Also called OEL or Original English Language manga, but "global" is more inclusive, since Japanese-influenced manga can of course be created in other languages besides English.
Harem A genre of manga or anime which usually involves a male character who is surrrounded by several females, most of whom are romantically interested in him. (Though there can be harem shows with a female surrounded by males.) See Wikipedia, Everything2, or TV Tropes.
Heké basically means "huh?" ...It's something that's said frequently by the hamsters on the anime Hamtaro (or at least by the title hamster). And I thought I heard Kagome say it once on Inuyasha- which is funny because the actress who voices her in the English dub also voices Hamtaro's owner Laura in the English dub of "Hamtaro"). But to the best of my knowledge it isn't used elsewhere, which is why for now I'm putting it on the anime page instead of the general lexicon page.
Henshin means "transformation," and may refer to various things such as a character turning into their magical form (e.g., Serena turning into Sailor Moon), or a mecha transforming (e.g., the Transformers). See Wikipedia or TV Tropes.
Hentai Japanese term for sexually explicit or perverse anime, manga or video games; or a derogatory term for someone or something that is sexually perverse. It's a stronger term than ecchi. See Wikipedia, TV Tropes, or Everything2.
Japanimation In Japan, "anime" refers to all kinds of animation, regardless of style, nation of origin, etc, and they sometimes use "Japanimation" to refer to Japanese anime. Outside of Japan, the term is sometimes used to refer to Japanese animation, instead of calling it "anime." This is in fact the term I heard probably a few years before I ever heard the word "anime," but most American fans of anime consider it rather crude, and would prefer you to use the proper term.
Josei Manga or anime targeted at teenage or young adult women. The female equivalent of seinen. See Wikipedia or TV Tropes.
Kawaii See general terms page.
Mahou shoujo Magical girl, a kind of anime or manga where girls... turn into magical girls... like Sailor Moon, for example. See Wikipedia, Everything2, or TV Tropes.
Manga Japanese comic books; but like anime, it can be made for various age groups, specific genders, or for pretty much anyone. See Wikipedia or Everything2.
Manga-ka Manga artist. See people page.
Mecha or sometimes just mech refers to large robot-like machines (such as Zoids or Gundams) which are piloted by people in many animes. But mecha are often either living or life-like. See Wikipedia, Everything2, or TV Tropes.
Meganekko. See people page.
Mobile suits are a sort of mechanized armor with weapons. It may be something not too much bigger than a person, like an actual suit one wears, or it may be more like a giant robot one pilots, such as a Gundam or other mobile suits seen in the various Gundam series. See Wikipedia.
Moe Literally "budding," it can also refer to a crush on a specific anime or manga character or type of character (and such characters can themselves be called moe). It can refer to a genre (or genres) of anime or manga involving such characters. It could also be an exclamation, when filled with such a feeling, similar to "kawaii!" or "squee!" See Wikipedia or TV Tropes.
Moe sangyo Literally "budding business," it refers to the current boom in industries relating to otaku, including anime, manga, and video games. See Wikipedia.
Nekomimi Literally, "cat ears." Refers to catgirl characters in anime or manga. You might actually use any of various terms for catgirls, like "neko shoujo," perhaps, or "neko onno," but I think nekomimi is the most prevalent term. See Wikipedia, Everything2, or TV Tropes.
Newtype is a more evolved human with ESP abilities, as introduced in the anime Mobile Suit Gundam It's also a major Japanese magazine about anime. Check out the US version's official website, or Wikipedia.
Omake Bonus features, extra material. Kinda like all the stuff they add to DVD's to make them seem more special and charge more for them... except omake is supposed to be like, free, I guess. See Wikipedia or TV Tropes.
Original English Language (or OEL) manga are comics which are originally written in English, usually by American or other Western artists. As such, it's not true manga, but it is drawn in the Japanese style of manga. See Wikipedia or TV Tropes. See also global manga.
Original Net Animation (or ONA) Anime released directly via the internet, rather than TV, movies, or OVA. See Wikipedia.
OST Original soundtrack.
Otaku Literally means "house" (as in "family"). But in slang, in Japan, it can be a greatly insulting term for a person with an all-consuming obsession. Elsewhere, it's a term some hard-core anime fans may apply to themselves, though I'm sure some would eschew this, not wanting to corrupt the word's proper, negative meaning. See Wikipedia, Everything2, or TV Tropes.
OVA stands for "original video animation." Over here in the states, we have something called "direct to video," which is *sometimes* looked on *somewhat* disdainfully. That is, sometimes movies fail to achieve a desired theatrical release, and so are released directly on video instead. However, many things are intended from the start to be released originally on video, especially sequels to Disney animated films (for example). No dishonor in that, right? Anyway, while there's tons of anime in Japan produced for television or theaters, there's also a great deal produced for video, and to the best of my knowledge, OVA holds no particular stigma whatever. It can be just as popular as any format, and is often considered even better. To the best, as I say, of my admittedly extremely limited knowledge. Oh yes... it's also sometimes called OAV, or "original animated video." In fact that may be more common than OVA, but both are acceptable, and I believe OVA is the first one I happened to ever hear of, so it's what sticks in my mind. See Wikipedia or Everything2.
Saabisu Service. Or more specifically, the word may be used for fanservice: Adding something to anime or manga which has no relevance to the story, in order to please fans. This includes, but is not limited to, sexual situations, such as gratuitous scenes of nude or scantily clad characters. See Wikipedia, Everything2, or TV Tropes.
Seinen means "young man," and can refer to anime or manga made for that demographic. The male equivalent of josei. See Wikipedia, Everything2, or TV Tropes.
Seiyuu Japanese term for voice actors. See people page.
Shoujo Can be used to refer to anime or manga which is targeted at girls. See Wikipedia, Everything2, TV Tropes.
Shoujo ai Girls' love. Refers to anime or manga about love and romance between girls. See also yuri (lower this page). Can also refer to lolicon (see sextual terms page).
Shounen Can be used to refer to anime or manga which is targeted at boys. See Wikipedia, Everything2, or TV Tropes.
Shounen ai Boy's love. Refers to anime or managa about love and romance between boys. Mostly involves bishounen, and is popular with girls. See Wikipedia or Everything2. See also yaoi (lower this page). Can also refer to shotacon (see sexual terms page).
Super-deformed (SD) Might sometimes refer to chibi characters in general, though I believe more appropriately it is used when more realistic-looking characters briefly transform into chibi versions of themselves, or their normal proportions just go out of whack (heads or facial features might enlarge), for comedic effect and/or to denote an extreme mood change. See Wikipedia, Everything2, or TV Tropes.
Sweat drop This will sometimes appear on or near a character's head to show they're feeling something like confusion or embarrassment, etc. See Wikipedia, Everything2, or TV Tropes.
Tankobon technically means a separate book (stand-alone, not part of a series), but in manga refers to a single volume (which may be part of a series), which collects several chapters (which were most likely originally printed in an anthology magazine) of an ongoing story. It may also refer to the format of such volumes, which are smaller and thicker than American comics. See Wikipedia.
Tareme means "drooping eyes," which can refer to a style of anime or manga in which the characters (usually female) have such eyes. It's a look that connotes such things as sadness or innocence. Very child-like and cute, but is also sometimes associated with hentai See also Tsurime. See Everything2 or TV Tropes.
Tsundere A character trait wherein a person seems at first distant or combative, but who turns out to really be sweeter, underneath. See Wikipedia or TV Tropes.
Tsurime The opposite of tareme, with characters whose eyes are drawn to connote strength or arrogance. See TV Tropes.
Yaoi Anime or manga about male homosexual love. More explicit and sexual than shounen ai (though less explicit than bara). See Wikipedia, TV Tropes, or Everything2.
Yuri Anime or manga about female homosexual love. More explicit and sexual than shoujo ai. Yuri also means "lily." See Wikipedia, TV Tropes, or Everything2.