WordWeb Online

1. Deficient in originality or creativity; lacking powers of invention
   "unimaginative development of a musical theme";
   - sterile, uninspired, uninventive
    
2. Dealing only with concrete facts
    
3. Lacking spontaneity, originality or individuality
   "even his profanity was unimaginative";
   - stereotyped, stereotypic, stereotypical

See also: conventional, mainstream, practical, uncreative

Encyclopedia: Unimaginative