English Reference
noun

dichotomy

n.
US /daɪˈkɑtəmi/ UK /daɪkˈɒtəmi/ di·choto·my UK spelling dichotomies

  1. 01 C1 Advanced Academic

    a division or contrast between two things that are seen as opposites.

    a division or contrast between two things that are represented as being opposed or entirely different.

    Simple

    There is a clear dichotomy between what the company says and what it actually does.

    In context

    The essay explores the dichotomy between public duty and private desire in nineteenth-century literature.

    Usage

    Often used with the preposition 'between'.

  2. 02 C2 Proficiency TechnicalAcademic Logic

    the division of a group into two parts that do not overlap.

    the division of a class or genus into two disjoint subclasses that are together comprehensive.

    Simple

    The biologist studied the dichotomy of the species into two distinct groups.

    In context

    In formal logic, a dichotomy requires that the two resulting categories be mutually exclusive and collectively exhaustive.

    Usage

    Common in scientific and philosophical contexts.

  3. 03 C2 Proficiency Technical Science

    the way a plant stem or a vein splits into two equal parts.

    a mode of branching by constant repeated division into two equal parts.

    Simple

    The plant is identified by the dichotomy of its stems as they grow upward.

    In context

    The fossil shows a clear pattern of dichotomy in the leaf veins, which helped researchers identify the ancient fern species.

    Usage

    Used specifically in botany and anatomy to describe physical structures.

    branchingforking
  4. 04 C2 Proficiency Technical Science

    a time when the moon or a planet looks half-lit from Earth.

    the phase of the moon or an inferior planet when half of its disk appears illuminated.

    Simple

    The moon reached dichotomy, appearing as a perfect half-circle in the night sky.

    In context

    Precise observations of Venus at dichotomy were historically significant for calculating the distance between the Earth and the Sun.

    Usage

    Refers to the specific geometric alignment of celestial bodies.

    half moonquadrature

Vollmann has spent his career refusing to distill the world into dichotomies.

The Conversation· 24 Aug 2026

But it also risks creating a false dichotomy where all AI programs are seen as responsive and motivating, and all classroom teaching is rote lecturing.

The Conversation· 13 Jul 2026

From Ancient Greek διχοτομία (dikhotomía, “dichotomy”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Ancient Greek διχοτομία
Level C1 · Advanced
Frequency Occasional
Updated