du·al   /ˈduəl, ˈdyu-/ Pronunciation Key - [doo-uhl, dyoo-] Pronunciation Key –adjective
1. of, pertaining to, or noting two. 
2. composed or consisting of two people, items, parts, etc., together; twofold; double: dual ownership; dual controls on a plane. 
3. having a twofold, or double, character or nature. 
4. 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. 5. the dual number. 
6. a form in the dual, as Old English git “you two,” as contrasted with ge “you” referring to three or more.