of, pertaining 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.

the dual number.

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

adjective

bifold , binal , binary , coupled , double , doubleheader , duple , duplex , duplicate , matched , paired , twin , biform , geminate , twofold , reciprocal