dichotomies

Noun

dichotomy (countable and uncountable, plural dichotomies)

1. A separation or division into two; a distinction that results in such a division.
   • The dichotomy between the private and the public is central to almost two centuries of feminist writing and political struggle; it is, ultimately, what the feminist movement is all about. Although some feminists treat the dichotomy as a universal, trans-historical and trans-cultural feature of...1989, Carole Pateman, 6: Feminist Critiques of the Public/Private Dichotomy: The Disorder of Women: Democracy, Feminism, and Political Theory, page 118

   Synonyms:

   bisection

2. Such a division involving apparently incompatible or opposite principles; a duality.
   • But we do not try to characterize the top and bottom parts of the brain in terms of a simple dichotomy or set of dichotomies, which was exactly what was done with the existing and well-known division of the brain into two halves: namely the left versus the right, the dominant pop-culture brain...2013 November 11, Stephen M. Kosslyn, G. Wayne Miller, “How the Brain Creates Personality: A New Theory”, in The Atlantic
3. The division of a class into two disjoint subclasses that are together comprehensive, as the division of human into female and male.
   • But in the fallacy of false dichotomy, not only do the two alternatives fail to be jointly exhaustive, but they are not even likely. As a result, the disjunctive premise is false, or at least probably false.2011, Patrick J. Hurley, A Concise Introduction to Logic, page 162
4. The division of a genus into two species; a division into two subordinate parts.

   Synonyms:

   partition, trichotomy

5. A phase of the moon when it appears half lit and half dark, for example at the quadratures.
   • The Ides of Januarius indeed, the preceding month, must have fallen on March 1 at midnight, two days before the first dichotomy of the mean new moon of that month, March 3 at midnight.1854, Edward Greswell, Origines Kalendariæ Italicæ: Tables of the Roman Calendar, volume 1, page 261
6. Division and subdivision; bifurcation, such as that of a stem of a plant or a vein of the body into two parts as it proceeds from its origin; often successive.
   • In one forked leaf there is a distinct vein dichotomy, and the leaf boundary commences 1.5 mm above the dichotomy.1969, J. F. Rigby, Permian Sphenopsids from Antarctica, Geological Survey Professional Paper 613-F, page F-9