[ doo-uh l, dyoo- ]
/ ˈdu əl, ˈdyu- /


of, relating to, or noting two.
composed or consisting of two people, items, parts, etc., together; twofold; double: dual ownership; dual controls on a plane.
having a twofold, or double, character or nature.
Grammar. being or pertaining to a member of the category of number, as in Old English, Old Russian, or Arabic, that denotes two of the things in question.

noun Grammar.

the dual number.
a form in the dual, as Old English git “you two,” as contrasted with ge “you” referring to three or more.

Origin of dual

1535–45; < Latin duālis containing two, relating to a pair, equivalent to du(o) two + -ālis -al1

Related forms

du·al·ly, adverb

Can be confused

dual duel
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for dually

  • Nimrod joined me at this moment and he was thanked separately and dually, for being the husband of his wife, I suppose.

    A Woman Tenderfoot|Grace Gallatin Seton-Thompson

British Dictionary definitions for dually


/ (ˈdjuːəl) /


relating to or denoting two
twofold; double
(in the grammar of Old English, Ancient Greek, and certain other languages) denoting a form of a word indicating that exactly two referents are being referred to
maths logic (of structures or expressions) having the property that the interchange of certain pairs of terms, and usually the distribution of negation, yields equivalent structures or expressions


  1. the dual number
  2. a dual form of a word

verb duals, dualling or dualled

(tr) British to make (a road) into a dual carriageway

Derived Forms

dually, adverb

Word Origin for dual

C17: from Latin duālis concerning two, from duo two
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012