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
serve as a teacher or trusted counselor; "The famous professor mentored him during his years in graduate school"; "She is a fine lecturer but she doesn't like mentoring"
tending to or capable of propelling; "propellant fuel for submarines"; "the faster a jet plane goes the greater its propulsive efficiency"; "universities...the seats of propulsive thought"