adjective 1.having the dimensions of height and width only: a two-dimensional surface.
2.(of a work of art) having its elements organized in terms of a flat surface, especially emphasizing the vertical and horizontal character of the picture plane: the two-dimensional structure of a painting.
3.(in a literary work) shallow, unconvincing, or superficial in execution: a novel having two-dimensional characters.
Origin:
1895–1900
Related forms two-di·men·sion·al·i·ty, noun
two-di·men·sion·al·ly, adverb