[ lok ]
See synonyms for: locklocked on Thesaurus.com

  1. a device for securing a door, gate, lid, drawer, or the like in position when closed, consisting of a bolt or system of bolts propelled and withdrawn by a mechanism operated by a key, dial, etc.

  2. a contrivance for fastening or securing something.

  1. (in a firearm)

  2. any device or part for stopping temporarily the motion of a mechanism.

  3. an enclosed chamber in a canal, dam, etc., with gates at each end, for raising or lowering vessels from one level to another by admitting or releasing water.

  4. an air lock or decompression chamber.

  5. complete and unchallenged control; an unbreakable hold: The congresswoman has a lock on the senatorial nomination.

  6. Slang. someone or something certain of success; sure thing: He's a lock to win the championship.

  7. Wrestling. any of various holds, especially a hold secured on the arm, leg, or head: leg lock.

  8. Horology. (in an escapement) the overlap between a tooth of an escape wheel and the surface of the pallet locking it.

  9. Metalworking. a projection or recession in the mating face of a forging die.

verb (used with object)
  1. to fasten or secure (a door, window, building, etc.) by the operation of a lock or locks.

  2. to shut in a place fastened by a lock or locks, as for security or restraint.

  1. to make fast or immovable by or as if by a lock: He locked the steering wheel on his car.

  2. to make fast or immovable, as by engaging parts: to lock the wheels of a wagon.

  3. to join or unite firmly by interlinking or intertwining: to lock arms.

  4. to hold fast in an embrace: She was locked in his arms.

  5. to move (a ship) by means of a lock or locks, as in a canal (often followed by through, in, out, down, or up).

  6. to furnish with locks, as a canal.

verb (used without object)
  1. to become locked: This door locks with a key.

  2. to become fastened, fixed, or interlocked: gears that lock into place.

  1. to go or pass by means of a lock or locks, as a vessel.

  2. to construct locks in waterways.

Verb Phrases
  1. lock in,

    • to commit unalterably: to lock in the nomination of the party's candidates.

    • (of an investor) to be unable or unwilling to sell or shift securities.

  2. lock off, to enclose (a waterway) with a lock.

  1. lock on,

    • to track or follow a target or object automatically by radar or other electronic means.

    • (in a video game) to target and then maintain the focus of the game camera and the player’s weapon on a selected character or item, though the player character and the targeted character may both be in motion.

  2. lock out,

    • to keep out by or as if by a lock.

    • to subject (employees) to a lockout.

  3. lock up,

    • to imprison for a crime.

    • Printing. to make (type) immovable in a chase by securing the quoins.

    • to fasten or secure with a lock or locks.

    • to lock the doors of a house, automobile, etc.

    • to fasten or fix firmly, as by engaging parts.

Idioms about lock

  1. lock horns, to come into conflict; clash: to lock horns with a political opponent.

  2. lock, stock, and barrel, completely; entirely; including every part, item, or facet, no matter how small or insignificant: We bought the whole business, lock, stock, and barrel.

  1. under lock and key, securely locked up: The documents were under lock and key.

  2. lock and load,

    • to load a gun with ammunition and prepare to fire: At twelve years old, I had to lock and load to protect the herd from cattle rustlers.

    • to ready oneself for action: Lock and load, gamers! The tournament starts in ten!

Origin of lock

First recorded before 900; Middle English; Old English loc “fastening, bar”; cognate with Middle Low German lok, Old High German loh, Old Norse lok “a cover, lid,” Gothic -luk in usluk “opening”; akin to Old English lūcan “to shut”

Other words from lock

  • lock·less, adjective
  • self-lock·ing, adjective
  • well-locked, adjective

Words Nearby lock

Other definitions for lock (2 of 2)

[ lok ]

  1. a tress, curl, or ringlet of hair.

  2. locks,

    • the hair of the head.

    • short wool of inferior quality, as that obtained in small clumps from the legs.

  1. a small tuft or portion of wool, cotton, flax, etc.

Origin of lock

before 900; Middle English locke,Old English locc lock of hair, cognate with Old Norse lokkr,Dutch lok curl, German Locke

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use lock in a sentence

British Dictionary definitions for lock (1 of 2)


/ (lɒk) /

  1. a device fitted to a gate, door, drawer, lid, etc, to keep it firmly closed and often to prevent access by unauthorized persons

  2. a similar device attached to a machine, vehicle, etc, to prevent use by unauthorized persons: a steering lock

    • a section of a canal or river that may be closed off by gates to control the water level and the raising and lowering of vessels that pass through it

    • (as modifier): a lock gate

  1. the jamming, fastening, or locking together of parts

  2. British the extent to which a vehicle's front wheels will turn to the right or left: this car has a good lock

  3. a mechanism that detonates the charge of a gun

  4. US and Canadian informal a person or thing that is certain to win or to succeed: she is a lock for the Academy Award

  5. lock, stock, and barrel completely; entirely

  6. any wrestling hold in which a wrestler seizes a part of his opponent's body and twists it or otherwise exerts pressure upon it

  7. Also called: lock forward rugby either of two players who make up the second line of the scrum and apply weight to the forwards in the front line

  8. a gas bubble in a hydraulic system or a liquid bubble in a pneumatic system that stops or interferes with the fluid flow in a pipe, capillary, etc: an air lock

  1. to fasten (a door, gate, etc) or (of a door, etc) to become fastened with a lock, bolt, etc, so as to prevent entry or exit

  2. (tr) to secure (a building) by locking all doors, windows, etc

  1. to fix or become fixed together securely or inextricably

  2. to become or cause to become rigid or immovable: the front wheels of the car locked

  3. (when tr, often passive) to clasp or entangle (someone or each other) in a struggle or embrace

  4. (tr) to furnish (a canal) with locks

  5. (tr) to move (a vessel) through a system of locks

  6. lock horns (esp of two equally matched opponents) to become engaged in argument or battle

  7. lock the stable door after the horse has bolted or lock the stable door after the horse has been stolen to take precautions after harm has been done

Origin of lock

Old English loc; related to Old Norse lok

Derived forms of lock

  • lockable, adjective

British Dictionary definitions for lock (2 of 2)


/ (lɒk) /

  1. a strand, curl, or cluster of hair

  2. a tuft or wisp of wool, cotton, etc

  1. (plural) mainly literary hair, esp when curly or fine

Origin of lock

Old English loc; related to Old Frisian lok, Old Norse lokkr lock of wool

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with lock


In addition to the idioms beginning with lock

  • lock horns
  • lock in
  • lock out
  • lock the barn door after the horse has bolted
  • lock up

also see:

  • under lock and key

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.