key
kee
Key (noun) means a shaped piece of metal used to open or lock a particular lock. Example: “She forgot her house key at the office again.”
noun
1
A shaped piece of metal used to open or lock a particular lock.
"She forgot her house key at the office again."
"He cut a spare key for his sister."
"I left my car key on the kitchen table this morning."
2
The single most important factor or step needed to achieve something.
"Practice is the key to learning any instrument."
"Patience was the key to solving the puzzle."
"Good communication is the key to a happy friendship."
3
One of the buttons pressed to type on a keyboard or play a musical instrument.
"The space bar is the widest key on the keyboard."
"He pressed a wrong key and the whole document changed."
"Press the escape key to close the window and go back."
4
A short guide listing what the symbols, colours, or abbreviations on a map, chart, or test mean.
"Check the key at the bottom of the map to see what the blue lines mean."
"The teacher provided an answer key for the exam."
"The key on the chart explains what each coloured line represents."
5
In music, the set of related notes a piece is built around, giving it its overall tonal centre.
"The song shifts from a major key to a minor one in the bridge."
"She transposed the piece into a lower key."
"The choir sang the hymn in the key of G major."
6
A code or piece of information used to lock or unlock encrypted data.
"The website uses a private key to secure your login details."
"Never share your secret key, or someone else could read your messages."
"The program creates a new key each time you send a protected file."
adj
1
Central or essential; of major importance.
"Cost was a key factor in choosing the smaller car."
"She played a key role in launching the new product."
"Trust is a key part of any good team."
How to use key
Learner’s notesIn plain EnglishMost often either the metal object that opens a lock, or (as an adjective) something essential and central to a situation.
Common mistake
Don't confuse the geographic sense (a low island, as in "the Florida Keys") with the everyday lock-opening object — they're unrelated in origin.
Common pairings
key to success
a key role
turn the key
key factor
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Word forms
- Plural
- keys
- Comparative
- keyer, more key
- Superlative
- keyest, most key
Fill the gap
Can you complete this real example?
She forgot her house _____ at the office again.
Etymology
From Old English cæg, of uncertain deeper origin, though it may ultimately trace back to a root meaning "stake" or "peg" — early keys were simple rods used to lift a bar across a door.
Synonyms
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Rhymes for key
See all rhymes for key →Frequently asked questions
What does “key” mean?
The word “key” means a shaped piece of metal used to open or lock a particular lock. In plain terms, most often either the metal object that opens a lock, or (as an adjective) something essential and central to a situation.
How do you pronounce “key”?
“Key” is pronounced kee (/ki/ in IPA).
How do you use “key” in a sentence?
Here is “key” used in a sentence: “She forgot her house key at the office again.”
What part of speech is “key”?
Depending on how it is used, “key” can be a noun and an adjective.
Where does the word “key” come from?
The word “key” comes from Old English. From Old English cæg, of uncertain deeper origin, though it may ultimately trace back to a root meaning "stake" or "peg" — early keys were simple rods used to lift a bar across a door.
Is “key” a common word?
“Key” is a very common word in modern English, usually learned at around the A1 level.
How many meanings does “key” have?
“Key” has 7 distinct senses listed in this dictionary. The most common is: a shaped piece of metal used to open or lock a particular lock.
What is the difference between a key and a lock?
A lock is the fixed mechanism that secures a door, drawer, or gate, while a key is the small shaped piece of metal that operates it. The two are made as a matched pair: the key's unique cuts fit the internal pins of one specific lock, so only that key can open it.
What are the types of keys?
Common types include house keys and car keys for everyday access, master keys that open several different locks in a building, and skeleton keys designed to work with many older locks. There are also padlock keys and safe keys. Each is cut to match the particular lock it is meant to operate.
What is an example of a key?
A familiar example is the metal house key you use to unlock your front door. When you slide it in and turn, its jagged edge lifts the pins inside the lock to exactly the right height, allowing the cylinder to rotate and the door to open. A car ignition key works on the same principle.
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