Definicija: to avoid detection by the entity one is observing, and especially to disguise one's own identity or use an assumed identity for the purposes of gaining the trust of an individual or organization to learn or confirm confidential information or to gain the trust of targeted individuals in order to gather information or evidence

Definicija: prikriti preiskovalni ukrep, ki se izvaja tako, da tajni delavec daljše časovno obdobje pod vodstvom in nadzorom policije zbira podatke o določeni osebi in njeni kriminalni dejavnosti in se pri tem vključi v njeno okolje