Imitating nature in man-made systems. Examples are a film similar to the coating on a moth's eyeballs that minimizes screen glare, a directional microphone that mimics the moving hairs on crickets, and a waterproof coating that emulates the grooves and wax coating on a butterfly's wings.
A very notable example is the Eastgate Center in Harare, Zimbabwe. Built in 1996, this shopping and office complex was constructed using principles discovered in termite mounds in the desert. Termites maintain an almost perfectly uniform temperature for their food inside their tunnels, even though outside temperatures range from near freezing at night to over 100 degrees Fahrenheit in the day. The even temperature is accomplished by continuously opening and closing a series of vents throughout the day. Eastgate uses 10% of the energy of a traditional building to keep cool. See bionic