1: the perception that something has occurred or some state exists; "early detection can often lead to a cure" [syn: sensing] 2: the act of detecting something; catching sight of something [syn: catching, espial, spying, spotting] 3: the detection that a signal is being received [syn: signal detection] 4: a police investigation to determine the perpetrator; "detection is hard on the feet" [syn: detecting, detective work, sleuthing] |