backdoor
n. countablen. a secret or hidden way to enter a building or a computer system. It can also mean a way to achieve something by avoiding the usual rules.
n. a secondary entrance at the rear of a building, or a hidden method for bypassing normal authentication in a computer system. Often used metaphorically to describe achieving an objective through indirect or unofficial channels.
The delivery driver used the backdoor to enter the kitchen.
Hackers exploited a backdoor in the software to access sensitive customer data without being detected.
While the official policy prohibited such hires, the manager found a backdoor through a temporary consulting contract to bring the specialist onto the team immediately.
From back + door.
Often used as a compound noun or as an attributive noun in phrases like 'backdoor deal' or 'backdoor entry'.