The term SEARCH FOR H2O can be summarized by the crossword solution DOWSE, which is a five-letter word. Dowsing is an ancient practice of using a divining rod to locate underground water sources. It is also known as water witching or divining. The practice has been used for centuries and is still used today in some parts of the world. By using a dowsing rod, a person can search for H2O, or water, beneath the surface of the earth.