The Collaborative International Dictionary of English v.0.48:
Dichotomous \Di*chot"o*mous\, a. [L. dichotomos, Gr. ?; ? in two, asunder + diate`mnein to cut.] Regularly dividing by pairs from bottom to top; as, a dichotomous stem. -- Di*chot"o*mous*ly, adv. [1913 Webster]WordNet (r) 3.0 (2006):
dichotomous adj 1: divided or dividing into two sharply distinguished parts or classifications