Ma'anar ƙamus na kalmar "aikin leken asiri" shine kamar haka:Aikin bincike yana nufin wani aiki ko aikin soja da aka yi don tattara bayanai game da abokan gaba ko wani yanki na musamman. Yawanci ya ƙunshi aika mutane ko ƙungiyoyi zuwa yanki don sa ido, tattara bayanan sirri, da bayar da rahoto game da matsayi, iyawa, niyya, ƙasa, ko duk wani bayani mai dacewa. Sojojin soji ne, hukumomin leken asiri, ko wasu gungun na musamman ne ke gudanar da ayyukan leken asiri, kuma suna taka muhimmiyar rawa wajen samun muhimman bayanai don taimakawa wajen tsara dabarun, zabin manufa, ko yanke shawara.