The words unless and until are often used together but their meanings are different, and often confused. Unless refers to a condition not being met while until refers to a time threshold not being crossed.
Comparison chart
 | Unless | Until |
|---|---|---|
| Meaning | Except for a specified condition. | Up to the time of (something happening); Before (a time). |
| Example | I will quit my job unless I get a pay hike. | You can go out and play until it gets dark. |
| Antonym | if | since |
| Pronunciation | IPA: /ənˈlɛs/, /ʌnˈlɛs/ | enPR: ŭntĭl', IPA: /ənˈtɪl/, SAMPA: /@n"tIl/ |
Meaning of Unless vs Until
The word until is used in the context of time and roughly means before and up to the time. For example,
- I cannot get to the TPS reports until next week.
- I lived with my parents until I was 17.
The word unless is used in the context of a precondition and means if this condition is not met. For example,
- I will not shoot that squirrel unless someone puts a gun to my head.
- Peter will not go to the picnic unless his dog is allowed to accompany him.
More examples
Here are some more examples for until and unless:
- The politician was afraid she would lose public support unless she expressed opposition to increased taxes.
- The city threatened to sue the factory for environmental pollution unless the company agreed to clean up the lake and install better filtration systems.
- The workers said they would continue to strike until their demands for a safer workplace were met.
- The party continued until the wee hours of the morning.
- Paul refused to take a shower until the water heater was fixed.
- The bank would repossess the car unless Neil made his loan payments.
Using the phrase 'unless and until'
The phrase unless and until is commonly used, which often leads to people thinking that the two words mean the same thing. However, this phrase should be used when the situation calls for both a context of time and a precondition. For example, Paul's mother told him that he will not get to play with any of his toys unless and until his homework is completed. In this sentence, completing the homework is a precondition, as well as connotes the time horizon after which Paul is allowed to play with his toys.
Advice 
Affect 
Then 
Quite 
Eminent 
Easy
Comments: Unless vs Until