A false positive is when a classification or decision system gives a positive result when it should really be negative; for example if a medical diagnosis system says someone has a disease, when they actually are healthy.
This is in contrast to with a true positive, a false negative or a true negative.
Used in Chap. 9: pages 130, 131, 140; Chap. 12: page 195; Chap. 18: pages 308, 310; Chap. 19: page 324; Chap. 20: page 345