unsuspecting
adj. B2 Upper Intermediate US //ˌənsəˈspɛktɪŋ// UK //ʌnsəspˈɛktɪŋ// un·sus·pect·ing
adj. not aware that something bad or dangerous is about to happen. You use this to describe someone who is easily tricked because they do not suspect any trouble.
adj. not aware of any impending danger or deception; lacking suspicion. Often used to describe the target of a prank, crime, or surprise.
The thief stole the wallet from an unsuspecting tourist.
The pranksters waited behind the door for an unsuspecting colleague to walk into the room.
The software update contained a hidden virus that quietly harvested data from thousands of unsuspecting users who believed they were simply improving their system's security.
Usage
Typically used attributively before the noun it modifies.