lock1

noun

• 1a mechanism for keeping a door, window, lid, or container fastened, typically operated by a key: the key turned firmly in the lock
• a device used to prevent the operation or movement of a vehicle or other machine:a steering lock a bicycle lock
• (in wrestling and martial arts) a hold that prevents an opponent from moving a limb.
• [in singular] archaic a number of interlocked or jammed items:I have seen all Albermarle Street closed by a lock of carriages

• 2a short section of a canal or river with gates and sluices at each end which can be opened or closed to change the water level, used for raising and lowering boats: there was a lock every quarter of a mile

• 3 [mass noun] British the turning of the front wheels of a vehicle to change its direction of motion.
• (also full lock) the maximum extent that the front wheels of a vehicle can be turned.

• 4 (also lock forward) Rugby a player in the second row of a scrum.

• 5 (a lock) North American informal a person or thing that is certain to succeed; a certainty: all of this makes him a lock to make the Hall of Fame

• 6 historical a mechanism for exploding the charge of a gun.

verb

• 1 [with object] fasten or secure (something) with a lock:she closed and locked her desk (as adjective locked)behind locked doors
• [no object] (of a door, window, etc.) become or be able to be secured with a lock:the door will automatically lock behind you
• [with object and adverbial] enclose or shut in by locking or fastening a door, lid, etc.:the prisoners are locked in overnight Phil locked away the takings

• 2make or become rigidly fixed or immovable: [with object]:he locked his hands behind her neck [no object]:their gaze locked for several long moments

• 3 [no object, with adverbial of direction] go through a lock on a canal:we locked through at Moore Haven