Adjective
1. consisting of or involving two parts or components usually in pairs;
"an egg with a double yolk""a double (binary) star""double doors""dual controls for pilot and copilot""duple (or double) time consists of two (or a multiple of two) beats to a measure"2. having more than one decidedly dissimilar aspects or qualities;
"a double (or dual) role for an actor""the office of a clergyman is twofold; public preaching and private influence"- R.W.Emerson"every episode has its double and treble meaning"-Frederick Harrison3. a grammatical number category referring to two items or units as opposed to one item (singular) or more than two items (plural);
"ancient Greek had the dual form but it has merged with the plural form in modern Greek"