A person who whistles is known as a WHISTLER. Whistling is an ancient form of communication, and it has been used for centuries to communicate over long distances. It is also used to express emotion or to create a pleasant atmosphere. The term 'WHISTLER' is derived from the Old English word 'hwistlian, ' which means 'to make a sound by blowing air through the lips.' The three-letter reference for this term is 'whs.'