where·of /-ˈʌv, ˈɑv/
1. Of which; of whom; formerly, also, with which; -- used relatively.
I do not find the certain numbers whereof their armies did consist. --Sir J. Davies.
Let it work like Borgias' wine,
Whereof his sire, the pope, was poisoned. --Marlowe.
Edward's seven sons, whereof thyself art one. --Shak.
2. Of what; -- used interrogatively.
Whereof was the house built? --Johnson.
adv 1: of which; "punishment for a crime whereof he was convicted"
2: of what; "he knows whereof he speaks"