A type of mythical creature in the science-fiction/fantasy world that exists in only two dimensions. Is incapable of seeing the third dimension. The most notable feature is that it is required to eat and excrete out of the same orfice. That is, if the digestive system had 2 openings, it would cut the organism in two.
A two-dimensional organism's mouth is also its anus.
Even an ameoba is not a two-dimensional organism.