Wordnet 3.0
ADJECTIVE (1)
1. 
 lacking the expected range or depth; 
 not designed to give an illusion or depth; 
- Example: "a film with two-dimensional characters"- Example: "a flat two-dimensional painting"[syn: two-dimensional, 2-dimensional, flat]
WordNet (r) 3.0 (2006):
2-dimensional
    adj 1: lacking the expected range or depth; not designed to give
           an illusion or depth; "a film with two-dimensional
           characters"; "a flat two-dimensional painting" [syn:
           two-dimensional, 2-dimensional, flat]