plural keys
1
a
: a usually metal instrument that is used to open a lock or to start or access a mechanism
my house/car keys
turned the key in the lock/ignition
… a metallic rattle, like keys being jangled.—
Derwent May
Derwent May2
a
: a means of gaining or preventing entrance, possession, or control
b
: an instrumental or deciding factor
the key to her success
3
a
: something that gives an explanation or identification or provides a solution
the key to a riddle
b
: a list of words or phrases giving an explanation of symbols or abbreviations
a pronunciation key in a dictionary
c
: an aid to interpretation or identification : clue
a key to understanding their motivation
e
: a map legend
4
a
: a part to be depressed by a finger that serves as one unit of a keyboard
also
: a representation of such a key (such as a space delineated on a touch screen)
Tiny keys on your iPhone's screen can be difficult to hit accurately. —Cherlynn Low
Cherlynn Low
b
: one of the levers of a keyboard musical instrument that actuates the mechanism and produces the tones
c
: a lever that controls a vent in the side of a woodwind instrument or a valve in a brass instrument
5
: a system of tones and harmonies generated from a hierarchical scale of seven tones based on a tonic
the key of G major
6
a
: characteristic style or tone
b
: the tone or pitch of a voice
c
: the predominant tone of a photograph with respect to its lightness or darkness
7
: a decoration or charm resembling a key
8
: a small switch for opening or closing an electric circuit
a telegraph key
9
: the set of instructions governing the encipherment and decipherment of messages
an encryption key
10
: a free-throw area in basketball : free throw lane
a jump shot from the top of the key
11
a(1)
(2)
: cotter
b
: a keystone in an arch
c
: a small piece of wood or metal used as a wedge or for preventing motion between parts
12
: samara
: extremely or crucially important
key issues
a key moment in the game
a key member of the staff
keyed; keying; keys
1
2
: to regulate the musical pitch of
key the strings
3
: to bring into harmony or conformity : make appropriate : attune
remarks keyed to a situation
4
: to identify (a biological specimen) by a key (see key entry 1 sense 3d)
5
: to provide with identifying or explanatory cross-references
instructions keyed to accompanying drawings—John Gartner
John Gartner6
: to make nervous, tense, or excited
—usually used with up
was too keyed up to sleep
7
: to enter or input (text or data) by using a keyboard
keying changes to a manuscript
—often used with in or intokey in a password
information being keyed into a database
8
: to be essential to : play the most important part in
defense keyed the victory
9
: to vandalize by scratching with a key
someone keyed my car door
1
: to use a key
2
: to observe the position or movement of an opposing player in football in order to anticipate the play
—usually used with on
The middle linebacker was keying on the halfback.
3
: to operate a machine by means of a keyboard : keyboard
: a low island or reef
slang
: a kilogram especially of marijuana or heroin
Examples of key in a Sentence
Noun (1)
in order to know what those dotted lines represent, you'll need to look at the key
a good education is the key to success
he had found the key to her heart
Adjective
He's a key player in the organization.
The key question is “Can we afford it?”.
Underline key words and phrases as you read.
Their votes were key in getting the bill passed.
Verb
The changes to the manuscript are being keyed by the typist.
her response was perfectly keyed to the situation
Recent Examples on the Web
Abbey Mastracco, New York Daily News, 19 June 2025
One key question — whether Combs himself would testify — has now been answered.
—Danielle Bacher, People.com, 18 June 2025
Angela Velasquez, Sourcing Journal, 4 June 2025
The fireworks scenes are particularly explosive with the animation keying up the characters’ emotional distance while showcasing the passion between them.
—Rafael Motamayor, Vulture, 4 June 2025
Jordan Rackie, Forbes.com, 20 June 2025
The key is its ability to penetrate the skin beyond the surface barrier.
—Kaleigh Werner, Footwear News, 20 June 2025
See All Example Sentences for key
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Adjective
The loss extended their losing streak to a season-high five games and cost them a series win over a key divisional opponent.
—Abbey Mastracco, New York Daily News, 19 June 2025
One key question — whether Combs himself would testify — has now been answered.
—Danielle Bacher, People.com, 18 June 2025
Verb
The brand keyed into the tradition of wearing orange on for the national holiday.
—Angela Velasquez, Sourcing Journal, 4 June 2025
The fireworks scenes are particularly explosive with the animation keying up the characters’ emotional distance while showcasing the passion between them.
—Rafael Motamayor, Vulture, 4 June 2025
Noun
Much of the work is behind-the-scenes—updating certificates, keys and secrets—but intrinsic to efficient, secure and well-managed operations.
—Jordan Rackie, Forbes.com, 20 June 2025
The key is its ability to penetrate the skin beyond the surface barrier.
—Kaleigh Werner, Footwear News, 20 June 2025
See All Example Sentences for key
Cite this Entry
“Key.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/key. Accessed 2 Jul. 2025.
Copy CitationKids Definition
key
1 of 4 noun
plural keys
1
a
: a small device that is used to open a lock or start an automobile
b
: a device having the form or function of a key
a key for winding a clock
2
: a means of gaining or preventing entrance, possession, or control
3
a
: something that provides an explanation, solution, or means of identifying
the key to a riddle
b
: a series of phrases or statements that describe characteristics by which plants or animals of a particular group differ and are used to aid in identification
c
: a map legend
4
: one of the levers with a flat surface that is pressed by a finger in operating a machine or playing an instrument
5
: a system of seven musical tones arranged in relation to a keynote from which the system is named
the key of C
6
: a characteristic style or tone
7
: a small switch for opening or closing an electric circuit
key
2 of 4 verb
keyed; keying
1
: to adjust the musical pitch of
2
: to bring into harmony
3
: to make nervous, tense, or excited
—usually used with up
all keyed up about the test
4
: to record by operating the keys of a machine
key each price into the cash register
key
3 of 4 adjective
: of great importance
the key people in the organization
the key question is "Can we afford it?"
use key words in an outline
key
4 of 4 noun
: a low island or reef
the Florida Keys
Etymology
Noun
Old English cǣg "key"
Noun
from Spanish cayo "a low island or reef"
Biographical Definition
Key 1 of 2
biographical name (1)
Francis Scott 1779–1843 American lawyer and author of "The Star-Spangled Banner"
Key
2 of 2biographical name (2)
John (Phillip) 1961– prime minister of New Zealand (2008–16)
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