The term POOL UNIT is composed of two words, LAP and GENE. LAP is a 3-letter word meaning to move in a circle around a fixed point, while GENE is a 4-letter word referring to a unit of heredity that is transmitted from a parent to offspring and is held to determine some characteristic of the offspring. Together, the two words form the term POOL UNIT, which is used to refer to a unit of water used for swimming or other recreational activities.