[di.chot.o.my] n, pl -mies [Gk dichotomia, fr. dichotomos] (1610) 1: a division or the process of dividing into two esp. mutually exclusive or contradictory groups or entities
2: the phase of the moon or an inferior planet in which half its disk appears illuminated 3 a: bifurcation; esp: repeated bifurcation (as of a plant's stem) b: a system of branching in which the main axis forks repeatedly into two branches c: branching of an ancestral line into two equal diverging branches
4: something with seemingly contradictory qualities