D defs.my
Entry 1 sense Webster, 1913

Dual

/d(y)o͞o'əl/ · Du·al · IPA /ˈdul/
01 a. Expressing, or consisting of, the number two; belonging to two; as, the dual number of nouns, etc. , in Greek.
  1. 1.
    Expressing, or consisting of, the number two; belonging to two; as, the dual number of nouns, etc. , in Greek.
    “Here you have one half of our dual truth.” Tyndall.