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"
(figurative) a course of action that is unproductive and offers no hope of improvement; "all the clues led the police into blind alleys"; "so far every road that we've been down has turned out to be a blind alley"