Definition of ONCE

ONCE Adverb, Conjunction and Noun

Once is a versatile word that can function as an adverb, conjunction, and noun. It generally denotes a single instance of something happening or being the case.

ONCE as an adverb

As an adverb, once indicates that something happened at some unspecified point in the past or will happen at a specific future time. For example, “She visited Paris once,” means she visited Paris on one occasion.

Single Occurrence: When used as an adverb, once emphasizes the singularity of an event or action. For instance, “I have only been to that restaurant once,” underscores that the visit happened just one time.

Frequency and Timing: Once can also refer to a particular time in the past or future, as in, “Call me once you arrive,” indicating the action should happen at the moment of arrival.

ONCE as a conjunction

As a conjunction, once introduces a subordinate clause and means “as soon as” or “after.” For example, “Once you finish your homework, you can watch TV,” indicates that watching TV is contingent on finishing homework.

Sequencing Actions: Using once as a conjunction helps in sequencing actions and events, providing a clear timeline for when something should happen. For instance, “Once the sun sets, the temperature drops,” explains the sequence of events.

ONCE as a noun

As a noun, once refers to one single time. For example, “Just this once, I’ll let you stay up late,” emphasizes that this is a one-time exception.

Emphasizing Uniqueness: In its noun form, once underscores the uniqueness or rarity of an occurrence. For instance, “This opportunity comes along once in a lifetime,” highlights the rarity and value of the opportunity.

Everyday Usage: In everyday conversation, once is frequently used to discuss past events, future plans, and to provide instructions based on conditions being met. For example, “She played the piano beautifully once,” recalls a specific event in the past.

Historical and Literary Contexts: Once is also used in storytelling and literature to set a scene or introduce a narrative, often seen in phrases like “Once upon a time,” which begins many traditional tales.

In conclusion, once is a multifaceted word that can function as an adverb, conjunction, and noun to denote a single instance of an event or action. It is instrumental in emphasizing the uniqueness of occurrences, sequencing actions, and providing clear temporal references in both everyday language and storytelling.

Examples of ONCE in a sentence

ONCE as an adverb in a sentence

  • Once, I visited Paris with my family.
  • She called me once last week.
  • I have only been to that restaurant once.
  • Once we finish this project, we’ll celebrate.
  • He was once a famous actor.
  • They met only once before getting married.
  • I went skydiving once and loved it.
  • She danced on stage once during a school play.Ç

ONCE as a conjunction in a sentence

  • Once you finish your homework, you can watch TV.
  • Once the meeting starts, please silence your phones.
  • Call me once you arrive at the airport.
  • He knew once he saw the results, he had passed.
  • Once you learn to ride a bike, you never forget.
  • Once they agreed on the terms, they signed the contract.
  • She started laughing once she understood the joke.
  • We can leave once everyone is ready.

ONCE as a noun in a sentence

  • You only have once to make a first impression.
  • Do it right the first time because you only get once.
  • For once, I agree with your decision.
  • She wished, just this once, that things would go smoothly.
  • He was late more than once last month.
  • She told him more than once to clean his room.
  • Let’s do it correctly at once.
  • Can we try it just this once?

Origin of ONCE

The term once has its etymological origins rooted in Old English and reflects temporal and conditional concepts associated with a single occasion or point in time.

  • Old English Roots: “Once” traces back to Old English as “ānes,” derived from “ān,” meaning “one.” In Old English, “ānes” denoted “once” or “on one occasion,” emphasizing singularity or uniqueness.
  • Temporal Connotations: Over time, the term “once” retained its emphasis on singularity but expanded to encompass temporal relationships. It signifies a specific point in time or a singular occurrence, often contrasted with recurring or continuous actions.
  • Conditional Usage: In addition to temporal connotations, “once” can also introduce conditional clauses, expressing the idea of “if at any time” or “if ever.” This conditional usage reflects the notion of a hypothetical or potential occurrence.
  • Contemporary Usage: In modern English, “once” is a versatile word used in various contexts to denote a singular occurrence or point in time. It is commonly employed in narratives, anecdotes, and conditional statements to provide clarity and specificity.

From its origins in Old English to its contemporary usage, the term once embodies the enduring concept of singularity and uniqueness in temporal and conditional relationships, enriching language with its nuanced meaning and usage.


  • Formerly
  • Previously
  • In the past
  • Once upon a time
  • At one time
  • Earlier
  • Before
  • In days gone by


  • Now
  • Presently
  • Currently
  • Nowadays
  • At this moment
  • At present
  • Today
  • Presently


  • Then
  • Once upon a time
  • Previously
  • Formerly
  • Before
  • In the past
  • In earlier times
  • In bygone days

🌐 🇬🇧 ONCE in other languages

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