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 on Chap. 9: pages 181, 196; Chap. 12: page 275; Chap. 18: pages 447, 450; Chap. 19: page 473; Chap. 20: pages 505, 506