Once vs. Until

Attribute	Once	Until
Definition	One time or on one occasion	Up to the point in time or event mentioned
Usage	Used to indicate a single occurrence	Used to indicate a continuous duration or limit
Duration	Short-term or immediate	Can be long-term or indefinite
Frequency	Occurs only once	Can occur multiple times until a certain point

Definition

Once and until are both temporal prepositions that are used to indicate a specific point in time or duration. Once is used to refer to a single occasion or event that happened at a particular time in the past. For example, "I went to Paris once." On the other hand, until is used to indicate the time up to which an action or state continues. For example, "I will wait until you arrive."

Usage

Once is often used to talk about something that happened in the past and is not expected to happen again. It is used to indicate a singular occurrence. For example, "I met him once at a party." Until, on the other hand, is used to indicate the duration of an action or state. It is used to show when something will stop or change. For example, "I will study until midnight."

Time Frame

Once typically refers to a specific point in time or a single occurrence. It does not imply any duration or continuation. For example, "I visited New York once in my life." Until, on the other hand, refers to a period of time that extends up to a certain point. It indicates the end of a particular action or state. For example, "I will wait until 5 o'clock."

Frequency

Once is used to indicate a singular event or occurrence. It suggests that something happened only one time. For example, "I only saw that movie once." Until, however, is used to indicate the duration of an action or state. It does not imply a specific number of times. For example, "I will work until I finish the project."

Expectation

Once is often used to express surprise or disbelief at a particular event happening. It can suggest that something unexpected occurred. For example, "I never thought I would see him again, but then I saw him once at the grocery store." Until, on the other hand, is used to indicate a planned or expected end point. It suggests that something will continue until a certain time or event. For example, "I will wait until you finish your meeting."

Conclusion

In conclusion, once and until are both temporal prepositions that are used to indicate time or duration. Once refers to a single occurrence or event that happened at a specific point in time, while until indicates the time up to which an action or state continues. Understanding the differences between these two prepositions can help you use them correctly in your writing and communication.