in case
- 1Used to introduce a possible event that someone prepares for or guards against.
Keep the receipt in case you need to return the jacket.
We left an hour early in case traffic was heavy on the interstate.
Note
Here the clause names a risk, and the main action is a hedge against it. You take the umbrella whether or not it rains. That is the test that separates it from the North American "if" use, where the main clause holds only when the condition does. A slightly formal variant puts should inside the clause (in case grandpa should stay to dine), which stresses how uncertain the event is.
- 2If; used to introduce a condition on which the main statement depends.
In case you haven't heard, the merger fell through last week.
In case the package arrives while I'm out, just sign for it.
Similarif
Note
North American English lets the phrase stand in for plain if: in case you need me, I'll be home all day. E. J. Guerin's Mountain Charley (1861) already uses it this way, weighing what would follow if she resumed her other character. Readers outside Canada and the US are more likely to hear a precaution than a condition. For an international audience, if is the unambiguous choice.
Practice
Can you tell the meanings of in case apart? Answer 2 quick questions from this page, or write your own sentence and AI will check it.