a system of means and activities whereby a social institution functions; "the complex machinery of negotiation"; "the machinery of command labored and brought forth an order"
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
the service (electric power or water or transportation) provided by a public utility; "the cost of utilities never decreases"; "all the utilities were lost after the hurricane"
a facility composed of one or more pieces of equipment connected to or part of a structure and designed to provide a service such as heat or electricity or water or sewage disposal; "the price of the house included all utilities"
the quality of being of practical use
a company that performs a public service; subject to government regulation
(economics) a measure that is to be maximized in any situation involving choice
characterized by the exactness or precision of mathematics; "mathematical precision"
statistically possible though highly improbable; "have a mathematical chance of making the playoffs"
beyond question; "a mathematical certainty"
of or pertaining to or of the nature of mathematics; "a mathematical textbook"; "slide rules and other mathematical instruments"; "a mathematical solution to a problem"; "mathematical proof"
operating or moving or allowing movement in one direction only; "a unidirectional flow"; "a unidirectional antenna"; "a unidirectional approach to a problem"