skeleton key 
noun
A key designed to fit many locks by having the interior of the bit hollowed.He slid a skeleton key into the lock, and eased the door open....
- Officer Humphrey put the skeleton key into the lock in order to get the door open.
- Taking a sharp breath in, she opened the package and found a heart shaped locket key chain with a skeleton key.
- protoctist
- Protoctista
- protoctistan
- protocultural
- protoculture
- proto-deacon
- protoderm
- proto-diasystem
- protodipnoan
- protodolomite
- protodynastic
- proto-Earth
- proto-Elamite
- protoenstatite
- Protoevangelion
- Protoevangelium
- protofibril
- protofilament
- protoform
- protogalactic
- protogalaxy
- protogastric
- protogeneous
- protogenetic
- protogenic