See more synonyms for lock 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a door, gate, lid, drawer, or the like in position when closed, consisting of a bolt or system of bolts propelled and withdrawn by a mechanism operated by a key, dial, etc.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.
  3. (in a firearm)
    1. the mechanism that explodes the charge; gunlock.
    2. safety(def 4).
  4. any device or part for stopping temporarily the motion of a mechanism.
  5. 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.
  6. an air lock or decompression chamber.
  7. complete and unchallenged control; an unbreakable hold: The congresswoman has a lock on the senatorial nomination.
  8. Slang. someone or something certain of success; sure thing: He's a lock to win the championship.
  9. Wrestling. any of various holds, especially a hold secured on the arm, leg, or head: leg lock.
  10. Horology. (in an escapement) the overlap between a tooth of an escape wheel and the surface of the pallet locking it.
  11. 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.
  3. to make fast or immovable by or as if by a lock: He locked the steering wheel on his car.
  4. to make fast or immovable, as by engaging parts: to lock the wheels of a wagon.
  5. to join or unite firmly by interlinking or intertwining: to lock arms.
  6. to hold fast in an embrace: She was locked in his arms.
  7. to move (a ship) by means of a lock or locks, as in a canal (often followed by through, in, out, down, or up).
  8. 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.
  3. to go or pass by means of a lock or locks, as a vessel.
  4. to construct locks in waterways.
Verb Phrases
  1. lock in,
    1. to commit unalterably: to lock in the nomination of the party's candidates.
    2. (of an investor) to be unable or unwilling to sell or shift securities.
  2. lock off, to enclose (a waterway) with a lock.
  3. lock on, to track or follow a target or object automatically by radar or other electronic means.
  4. lock out,
    1. to keep out by or as if by a lock.
    2. to subject (employees) to a lockout.
  5. lock up,
    1. to imprison for a crime.
    2. Printing.to make (type) immovable in a chase by securing the quoins.
    3. to fasten or secure with a lock or locks.
    4. to lock the doors of a house, automobile, etc.
    5. to fasten or fix firmly, as by engaging parts.
  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.
  3. under lock and key, securely locked up: The documents were under lock and key.

Origin of lock

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
Related formslock·less, adjectiveself-lock·ing, adjectivewell-locked, adjective


  1. a tress, curl, or ringlet of hair.
  2. locks,
    1. the hair of the head.
    2. short wool of inferior quality, as that obtained in small clumps from the legs.
  3. 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. 2019

Examples from the Web for lock

Contemporary Examples of lock

Historical Examples of lock

  • You see, Uncle Paul, you are growing old and forgetful, and might lock me in again.

    Brave and Bold

    Horatio Alger

  • Andrew Lanning slipped to the door and turned the key in the lock.

  • She glided to the door into the hall and turned the lock softly and came to him again.

  • It was pushed to, but not locked, and had no fastening upon it except the lock, in which was the key.

    Weighed and Wanting

    George MacDonald

  • "Let me open it for you," he said, taking the key from her hand and inserting it in the lock.

    The Foolish Lovers

    St. John G. Ervine

British Dictionary definitions for lock


  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 personsa steering lock
    1. 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
    2. (as modifier)a lock gate
  3. the jamming, fastening, or locking together of parts
  4. British the extent to which a vehicle's front wheels will turn to the right or leftthis car has a good lock
  5. a mechanism that detonates the charge of a gun
  6. US and Canadian informal a person or thing that is certain to win or to succeedshe is a lock for the Academy Award
  7. lock, stock, and barrel completely; entirely
  8. any wrestling hold in which a wrestler seizes a part of his opponent's body and twists it or otherwise exerts pressure upon it
  9. 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
  10. 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, etcan 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
  3. to fix or become fixed together securely or inextricably
  4. to become or cause to become rigid or immovablethe front wheels of the car locked
  5. (when tr, often passive) to clasp or entangle (someone or each other) in a struggle or embrace
  6. (tr) to furnish (a canal) with locks
  7. (tr) to move (a vessel) through a system of locks
  8. lock horns (esp of two equally matched opponents) to become engaged in argument or battle
  9. 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
Derived Formslockable, adjective

Word Origin for lock

Old English loc; related to Old Norse lok


  1. a strand, curl, or cluster of hair
  2. a tuft or wisp of wool, cotton, etc
  3. (plural) mainly literary hair, esp when curly or fine

Word Origin for 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

Word Origin and History for lock

"means of fastening," Old English loc "bolt, fastening; barrier, enclosure," from Proto-Germanic *lukan (cf. Old Norse lok "fastening, lock," Gothic usluks "opening," Old High German loh "dungeon," German Loch "opening, hole," Dutch luik "shutter, trapdoor"). "The great diversity of meaning in the Teut. words seems to indicate two or more independent but formally identical substantival formations from the root."

The Old English sense "barrier, enclosure" led to the specific meaning "barrier on a river" (c.1300), and the more specific sense "gate and sluice system on a water channel used as a means of raising and lowering boats" (1570s). Wrestling sense is from c.1600. Phrase under lock and key attested from early 14c.


"tress of hair," Old English locc "lock of hair, curl," from Proto-Germanic *lukkoz (cf. Old Norse lokkr, Old Saxon, Old Frisian, Dutch lok, Old High German loc, German Locke "lock of hair"), from PIE *lugnos-, perhaps related to Greek lygos "pliant twig, withe," Lithuanian lugnas "flexible."


"to fasten with a lock," c.1300, from Old English lucan "to lock, to close" (class II strong verb; past tense leac, past participle locen), from the same root as lock (n.1). Cognate with Old Frisian luka "to close," Old Saxon lukan, Old High German luhhan, Old Norse luka, Gothic galukan. Meaning "to embrace closely" is from 1610s. Related: Locked; locking. Slang lock horns "fight" is from 1839.

Online Etymology Dictionary, © 2010 Douglas Harper

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.