Dichotomy [ from online dictionary]

dichotomy
dʌɪˈkɒtəmi,dɪ-/
noun
noun: dichotomy; plural noun: dichotomies
  1. 1.
    a division or contrast between two things that are or are represented as being opposed or entirely different.
    “a rigid dichotomy between science and mysticism”
    synonyms: division, separation, divorce, split, gulf, chasm;

    “there is a great dichotomy between social theory and practice”
  2. 2.
    BOTANY
    repeated branching into two equal parts.
Origin
late 16th century: via modern Latin from Greek dikhotomia, fromdikho- ‘in two, apart’ + -tomia (see -tomy).