The word "lock" refers to a device or mechanism used to secure or fasten something, such as a door or a container, by preventing it from opening without the correct key, combination, or code. Full definition
His guidance helped in locking in an extremely attractive rate with closing costs that were the best we have ever seen. (mattscottstl.com)
Power door lock on driver's side has stopped working. (autolist.com)
Maybe it's a symptom of dealing with too many types of lock screens on too many platforms and devices, but it took us a while to get used to this particular feature. (pocketnow.com)