0 a small lock that is opened using a set of numbers or letters put in a particular order, usually by turning wheels with numbers on them or by pressing keys: --
Evidence is kept behind a steel door secured by a combination lock.
The briefcase had a combination lock.
The front door key is kept in a keysafe with a combination lock.
He punched the keypad on the combination lock and the heavy door swung open.
Someone had fitted a combination lock to the back gate.
He laid the suitcase on the bed, turned the combination locks and lifted the lid.
Case files are kept at police headquarters behind two sets of doors, with the outer doors secured with a combination lock.