a type of statement based on or reducible to a true false condition —note 1. a Boolean operator is a key word that specifies how to combine simple logical expressions into complex expressions; Boolean operators negate a predicate (NOT), specify a combination of predicates (AND), or specify a list of alternative predicates (OR), e.g., the use of AND in the expression DEPTH > 100 AND GPM > 500 —note 2. other Boolean operators are available, such as XOR, CAND, COR, and CXOR —note 3. loosely, but erroneously, a logical expression such as DEPTH greater than 100 This definition last updated 07/17/2008