unless
- 01 B1 Intermediate
you use this to mean 'except if'. It shows that one thing will happen only if another thing does not happen.
introduces a condition that must be met to prevent a particular outcome. It is functionally equivalent to 'if... not' in most real or predictive conditional sentences.
Simple“We will have the picnic outside unless it starts to rain.”
In context“The merger will proceed as scheduled unless the regulatory body finds evidence of a conflict of interest during the final audit.”
PitfallI will go to the park unless it will rain. I will go to the park unless it rains.In clauses starting with 'unless' that refer to the future, use the present simple tense, not 'will'.
Synonymsexcept ifsave that - 02 B2 Upper Intermediate
used to talk about an imaginary situation that would have changed the result.
used to introduce an exception to a hypothetical or counterfactual statement, often following a conditional 'would' clause.
Simple“I wouldn't have called you so late unless it was an emergency.”
In context“The witness stated she would not have approached the vehicle unless she had heard a cry for help coming from the back seat.”
Synonyms
From Middle English unlesse, earlier on lesse (modern on + less), from (not) on lesse (than) (“(not) on a less compelling condition (than)”). The quality of negation in the word and the lack of stress changed on to un-.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.