di·chot·o·my

 
Pronunciation: dI-'kä-t&-mE also d&-
Function: noun
Inflected Form(s): plural -mies
Etymology: Greek dichotomia, from dichotomos
1 : a division or the process of dividing into two especially 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; especially : 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

Merriam-Webster Dictionary