It means “to delay or prevent something by acting ahead of time”.
For example,
To forestall illness, wash your hands after using the bathroom.
http://www.merriam-webster.com/dictionary/forestall
It means “to delay or prevent something by acting ahead of time”.
For example,
To forestall illness, wash your hands after using the bathroom.
http://www.merriam-webster.com/dictionary/forestall