warn in advance or beforehand; give an early warning;
"I forewarned him of the trouble that would arise if he showed up at his ex-wife's house"
- We had been forewarned of the risk of fire.
- The fishermen were forewarned of the oncoming of the storm.
We were forewarned of your coming And shut the gates.出自：3 Henry VI , Shakespeare
Forewarned is forearmed.出自：Proverb