次元 [cì yuán]
n. Originating from the Japanese ACG culture, this Internet slang term refers to a collection of elements in fantasy worlds. A typology of such worlds witnesses 1-, 2-, and, 3-dimensional worlds as known in common sense.
However, an 2.5-dimensional character is one created in a 2-dimensional world but highly fictitious. A 2-dimensional world resident is a reader who is highly interested in ACG fictitious characters but shows little interest in the world that he or she exists. A 4-dimensional world resident is not enamored with ACG fictitious characters but lives in his or her own world. A 3-dimensional world resident, however, is zealous towards reality.