An oscillator is an HFOV.
2. An oscillator is a medical device used in the hospital when a conventional ventilator isn't working, and/or the patient's lungs are to fragile to tollerate opening, and closing. It shoots several hundred breaths per minute into the patient's lungs at very small puffs, so the lungs can rest, and they don't have to open and close, and while they are resting, the patient is still being ventilated.

Someone people turn to when they're sad who makes them feel better.