bimodal

from WordNet (r) 3.0 (2006)

bimodal
    adj 1: of a distribution; having or occurring with two modes
           [ant: {unimodal}]

from The Collaborative International Dictionary of English v.0.48

bimodal \bimodal\ adj. (Statistics)
   having or occurring with two {modes[9]}; having two maxima;
   -- of a curve or distribution. {unimodal}
   [WordNet 1.5]