단 한 번만 일어나는 일이나 횟수를 나타냄.
On one occasion or for one time only.
예문:
"I have only visited Paris once in my life."
"The software should be updated at least once a year."
과거의 어느 시점에 존재했거나 일어났던 상태를 나타냄.
At some time in the past; formerly.
예문:
"This quiet village was once a bustling industrial hub."
"She once believed that anything was possible with hard work."
부정문이나 조건문에서 강조를 위해 사용되어 한 번이라도 있음을 나타냄.
At all or on even one occasion, used for emphasis in negative or conditional sentences.
예문:
"He did not once apologize for the mistake he made."
"If you once lose your credibility, it is very hard to regain."
어떤 일이 일어나는 즉시 또는 그 시점부터를 나타냄.
As soon as; from the moment that.
예문:
"Once the contract is signed, we can begin the project."
"You will understand the rules once you start playing."
과거에는 그러했으나 현재는 더 이상 그렇지 않은 상태를 수식함.
Having been such in the past but no longer so.
예문:
"The once famous actor now lives a quiet life in the countryside."
"She revisited her once childhood home after twenty years."