An animation style were the animator make his/her animated cartoon emulate silent films of the 1890s-1930s.Or the animated cartoon emulates old film stock from 1940s-1970s.Other forms of Retro-mation may also be made to have a grainy appearance to emulate the classic era of film in Hollywood from the 1930s-1960s. Not all Retro-mation needs to be in black and white but it adds a Nostalgic effect to the cartoon.
This style is very common in Flash Animation.
any cartoon that is Japanese and then translated into English. Some examples are Dragon Ball Z, Voltron, or Astro boy. Usually the story revolves around fighting, and the animation is limited. There is both good and bad Japan-a-mation, for instance: FLCL-good(good animation, with original story with a lot of underlying subtext for both a older teen and adult audience). Yu-gi-oh - BAD(why do you want to watch other people play a card game, and the plot seems as if the writer just makes the crap up as he goes).
Oh snap, Goku just ripped that guys eyes out from the back of his head. That's some good japan-a-mation.