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"
air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time
breathing device consisting of a bent tube fitting into a swimmer's mouth and extending above the surface; allows swimmer to breathe while face down in the water
marked by skill in deception; "cunning men often pass for wise"; "deep political machinations"; "a foxy scheme"; "a slick evasive answer"; "sly as a fox"; "tricky Dick"; "a wily old attorney"
intended to deceive; "deceitful advertising"; "fallacious testimony"; "smooth, shining, and deceitful as thin ice" - S.T.Coleridge; "a fraudulent scheme to escape paying taxes"