Comes from the words fad and anime put together.
An anime series that, when it first comes out, is extremely popular, but then people just forget about it afterwards.
Ouran Host Club was such a fadime. I hardly see fanart of it anymore.
Fullmetal Alchemist is so NOT a fadime! It's still all over the place!
From putting the words "fad" and "anime" together. It means an anime or a series that gets adapted into one that starts or starts up a quick and high popularity. TV Tokyo had aired some of these kinds of anime starting in Japan.
Medabots - Oriinally started out as a video game. It was adapted into a two season anime with the same name and a sequal anime, Medabots Spirit. They revolve around customizable robots with A.I.(Artificial Intelligence). It's one of my favorite anime.
Beyblade - Adapted from a Manga about spinning tops. Created by Takao Aoki, which his work is mostly around toys and games.
Bakugan - An anime series that's produced by TMS Entertainment and Japan Vistec and directed by Director Mitsuo Hashimoto. It's adapted into a strategy game with the same name by Sega and Spin Master.