[du.al] adj [L dualis, fr. duo two--more at two] (1607) 1 of grammatical number: denoting reference to two
2. a: consisting of two parts or elements or having two like parts: double b: having a double character or nature -- du.al.ly adv
[2]dual n (1650) 1: the dual number of a language
2: a linguistic form in the dual