a mechanism consisting of a metal honeycomb through which hot fluids circulate; heat is transferred from the fluid through the honeycomb to the airstream that is created either by the motion of the vehicle or by a fan
heater consisting of a series of pipes for circulating steam or hot water to heat rooms or buildings
a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return; "sonar is an acronym for sound navigation ranging"; "asdic is an acronym for antisubmarine detection investigation committee"