ventilator (ven-ti-lay-ter) n.
1. a device used to ensure a supply of fresh air.

2. (respirator) equipment that is manually or mechanically operated to maintain a flow of air into and out of the lungs of a patient who is unable to breathe normally. cuirass v. a negative-pressure ventilator that encloses the chest. Drinker v. (iron lung) a negative-pressure ventilator that encloses the entire body except the head: replaced by the cuirass ventilator. negative-pressure v. an airtight container in which the air pressure is decreased and increased mechanically. This draws air into and out of the patient's lungs through the normal air passages. positive-pressure v. equipment that blows air into the patient's lungs; air is released from the lungs when the pressure from the ventilator is relaxed (see BiPAP, Nippy, noninvasive ventilation).

ven·ti·la·tor / ˈventəˌlātər/ • n. 1. an appliance or aperture for ventilating a room or other space. 2. Med. an appliance for artificial respiration; a respirator.