forewarn Meaning, Definition & Usage

verb warn in advance or beforehand; give an early warning
previse.
- I forewarned him of the trouble that would arise if he showed up at his ex-wife's house

imperfect & past participle Forewarned ; present participle & verbal noun Forewarning

To warn beforehand; to give previous warning, admonition, information, or notice to; to caution in advance.
We were forewarned of your coming. Shak.