Lock out vs. Lockout – Which is Correct?

The key distinction between lock out and lockout lies in their grammatical function: lock out (two words) is a phrasal verb meaning to prevent access, while lockout (one word) is a noun referring to the act or instance of locking someone or something out, often in an industrial context. Both are correct, but their usage depends entirely on whether you need a verb or a noun.

This grammatical distinction is crucial for many common word pairs, including the often-confused Log In vs. Login.

lock out or lockout – Which is Correct?

Both “lock out” and “lockout” are grammatically correct in American English, but they serve different purposes. The two-word phrase, lock out, functions as a phrasal verb. This means it describes an action, such as preventing someone from entering a building, excluding a player from a game, or disabling an account. The one-word term, lockout, is a noun. It refers to the event, situation, or state of being locked out. This is most commonly encountered in industrial disputes where an employer prevents employees from working, but it also applies to being denied access, such as a computer lockout.

The Best Trick to Remember the Difference

To remember the difference, think about the part of speech you need:

• If you are describing an action, use the two-word verb phrase: lock out. (e.g., “They will lock out the employees.”)
• If you are describing a thing, an event, or a state, use the one-word noun: lockout. (e.g., “The lockout lasted for weeks.”)

A simple “swap test” can also help: If you can replace the phrase with another verb like “exclude” or “bar,” use “lock out.” If you can replace it with a noun like “exclusion” or “shutdown,” use “lockout.”

Word	Part of Speech	Meaning	Example
lock out	Phrasal Verb	To prevent someone or something from entering or participating; to exclude.	The system will lock out users after three failed login attempts.
lockout	Noun	An act of locking out; the exclusion of employees by an employer from their place of work during a dispute; a security measure preventing access.	The industrial lockout devastated the local economy.

How to Use lock out

“Lock out” is a versatile phrasal verb that implies an action of exclusion or denial of access. It can be used in various contexts, from physically preventing entry to digitally restricting access or even excluding someone from a group or activity. It is always used in a sentence where an agent performs the action of “locking” someone or something “out.” The tone is generally neutral, simply describing the action.

Example 1: Don’t forget your keys, or you’ll lock out yourself from the house.

Example 2: The company decided to lock out the striking workers until a new agreement was reached.

Example 3: If you enter the wrong password too many times, the system will automatically lock out your account.

What are the different forms of lock out?

As a phrasal verb, “lock out” conjugates like the verb “lock.” The “out” remains constant.

• Base form: lock out (We need to lock out unauthorized personnel.)
• Past tense: locked out (She accidentally locked out her roommate.)
• Past participle: locked out (They have been locked out of the building.)
• Present participle/Gerund: locking out (The security guard is locking out the latecomers.)
• Third-person singular present: locks out (He always locks out the cat at night.)

Etymology of the word lock out

The phrasal verb “lock out” is formed from the Old English verb “locan,” meaning “to fasten, close, bar,” combined with the adverb “out.” The concept of using “lock” to mean securing something and “out” to denote exclusion has been present in English for centuries. The specific phrasal verb “lock out” became common as technologies and social situations evolved to include various forms of exclusion.

How to Use lockout

“Lockout” is a noun that refers to the consequence or the event of preventing access. Its most prominent use is in labor relations, where an employer implements a “lockout” to pressure employees during a dispute. However, it also describes any situation where access is denied, such as a “computer lockout” or a “security lockout.” When used, it often signifies a state of being excluded or the mechanism by which exclusion occurs.

Example 1: The management announced a sudden lockout, preventing all union members from entering the factory.

Example 2: After the server crash, many users experienced a temporary system lockout.

Example 3: The city’s emergency protocols included a complete traffic lockout during the parade.

What are the different forms of lockout?

As a noun, “lockout” primarily has a singular and plural form.

• Singular: lockout (The recent lockout caused significant financial losses.)
• Plural: lockouts (There have been several industrial lockouts in the past decade.)

Etymology of the word lockout

The noun “lockout” emerged in the English language in the mid-19th century, specifically around the 1850s. It developed directly from the phrasal verb “lock out,” combining the two words into a single noun to describe the act or instance of being locked out, particularly in the context of industrial disputes. This type of compound noun formation is common in English, where a verb phrase describing an action is converted into a noun to describe the event or result of that action.

Related Concepts

Understanding broader grammatical concepts can help clarify the correct usage of “lock out” and “lockout.”

• Phrasal Verbs: “Lock out” is an example of a phrasal verb, which is a verb combined with an adverb or a preposition (or both) to give a new meaning. Phrasal verbs often have idiomatic meanings that are not immediately obvious from the individual words. Recognizing them as single conceptual units that describe actions is crucial.
• Compound Nouns: “Lockout” is a compound noun, formed by combining two or more words to create a single noun with a new meaning. These can be written as one word (like “lockout,” “firefighter”), two words (“ice cream,” “bus stop”), or hyphenated (“sister-in-law”). Understanding that “lockout” is a single noun helps distinguish it from the verb phrase.

Examples from Media and Literature

• “The union called for a strike, but management responded with an immediate lockout.” – The New York Times, June 1, 2026.
• “If you fail to authenticate, the security system will lock out your credentials for ten minutes.” – From a technical manual for a new software release.
• “He found himself locked out of his own apartment after misplacing his keys, a truly frustrating predicament.” – A contemporary novel.
• “The league’s prolonged lockout threatened to cancel the entire season, disappointing fans across the country.” – A sports news article.
• “They had to lock out the old system before migrating all the data to the new platform.” – A business report on digital transformation.

Practice Exercises

Choose the correct word to complete the sentence.

1. The company faced a severe ___ due to the labor dispute.
2. Don’t forget to ___ the backdoor before you leave.
3. Employees were prepared for a long ___, but a resolution was quickly found.
4. If you keep trying to access that file, the system will ___ you.
5. The security system initiated a full ___ after detecting an intrusion.

Answer Key

1. lockout
2. lock out
3. lockout
4. lock out
5. lockout

lock out Synonyms

Synonym	Definition
Exclude	To deny someone access to a place, group, or privilege.
Bar	To prevent entry or exit; to prohibit.
Keep out	To prevent someone or something from entering.
Shut out	To prevent from entering or participating; to exclude.

lockout Synonyms

Synonym	Definition
Exclusion	The act of excluding or the state of being excluded.
Shutdown	A cessation of operation, often temporary.
Barring	The act of preventing entry or access.
Stoppage	A temporary halt in activity or work.

Frequently Asked Questions

Question 1: Can “lockout” (one word) be used as a verb?
No, “lockout” is exclusively a noun. To describe the action, you must use the phrasal verb “lock out” (two words).

Question 2: What is the most common mistake people make with these terms?
The most common mistake is using “lockout” (the noun) when they intend to use the verb “lock out.” For example, writing “The system will lockout your account” instead of “The system will lock out your account.”

Question 3: Does the context of industrial relations always mean “lockout”?
Yes, in the context of industrial disputes where an employer denies workers access, the term is always the noun “lockout.” For example, “The union called a strike; the company responded with a lockout.” If you were to describe the action from the company’s perspective, you would say, “The company decided to lock out the workers.”

Conclusion

The distinction between “lock out” and “lockout” is a clear example of how a small spacing difference can completely change a word’s meaning and grammatical function. Remember that lock out (two words) is the phrasal verb, describing the action of preventing access or excluding. Conversely, lockout (one word) is the noun, referring to the event, state, or instance of such an exclusion. Mastering this difference ensures clarity and precision in your writing, whether you’re discussing security protocols, labor disputes, or simply misplacing your keys.

Pro Tip: Always consider the part of speech required in your sentence. If you need an action, use the two-word verb. If you need to name the event or state, use the one-word noun. Correct usage enhances your professional reputation and ensures your message is understood exactly as intended.