1. strumentation which uses interference patterns between two waves to determine parameters of a wave. This can be used in optics, electronics, radio, astronomy, and acoustics.

2. An effect similar to an interference pattern. (Beardon)

3. Certain natural objects could be technically said to be interferometers, including planets, the human brain, and quartz crystals. What they have in common is a bipolar structure, which can serve simultaneously as a generator and background for detecting interference patterns. (Beardon)