in case

in case  {adv. phr.},  {informal}

1. In order to be prepared; as a precaution; if there is need. — Usually used in the phrase "just in case".

The bus is usually on time, but start early, just in case.

The big dog was tied up, but John carried a stick, just in case.

2. in case or in the event  {conj.}

If it happens that; if it should happen that; if; lest.

Tom took his skates in case they found a place to skate.

Let me know in case you're not coming.

The night watchman is in the store in case there is ever afire.

Keep the window closed in case it rains.

I stayed home in case you called.

In the event that our team wins, there will be a big celebration.