The Collaborative International Dictionary of English v.0.48:

Unidimensional \Un`i*di*men"sion*al\, a. [Uni- + dimensional.]
   (Math.)
   Having but one dimension. See Dimension.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unidimensional
    adj 1: relating to a single dimension or aspect; having no depth
           or scope; "a prose statement of fact is unidimensional,
           its value being measured wholly in terms of its truth"-
           Mary Sheehan; "a novel with one-dimensional characters"
           [syn: unidimensional, one-dimensional] [ant:
           multidimensional]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "unidimensional":
   monadal, monadic, one-piece, one-sided, uniangulate, unibivalent,
   unibranchiate, unicameral, unicellular, unicuspid, unidentate,
   unidigitate, unidirectional, uniflorous, unifoliate, unifoliolate,
   unigenital, uniglobular, unilateral, unilinear, uniliteral,
   unilobed, unilobular, unimodular, unimolecular, uniocular, unipart,
   unipartite, unipolar, univalent, univocal