dichotomically

noun, plural di·chot·o·mies.

division into two parts, kinds, etc.; subdivision into halves or pairs.
division into two mutually exclusive, opposed, or contradictory groups: a dichotomy between thought and action.
Botany. a mode of branching by constant forking, as in some stems, in veins of leaves, etc.
Astronomy. the phase of the moon or of an inferior planet when half of its disk is visible.

noun plural -mies

division into two parts or classifications, esp when they are sharply distinguished or opposedthe dichotomy between eastern and western cultures
logic the division of a class into two mutually exclusive subclassesthe dichotomy of married and single people
botany a simple method of branching by repeated division into two equal parts
the phase of the moon, Venus, or Mercury when half of the disc is visible

c.1600, from Greek dichotomia “a cutting in half,” from dicha “in two, asunder” (related to dis “twice”) + temnein “to cut” (see tome).