An example of whom is someone asking which person someone is speaking to, "To whom are you speaking?"
Whom did you ask?
To whom are you referring? With whom were you talking?
He's a person with whom I work.; We have ten employees, half of whom are carpenters.
Origin of whom
- Middle English from Old English hwǣm, hwām kwo- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition
- Old English hwam