"Ad hominem" or "ad hom" means 'to the man' or 'to the person'.
It's the label of a particular logical fallacy where somebody resists a person's
reasoning or argument by attacking the value of the person.
"Senator Silage is recommending that we should reduce the quarterly tax
on farm products in order to stimulate the small-farm economy of the midwest
states. Would anyone like to comment on that suggestion ?"
"Yes, I would. Everyone knows that Senator Silage did drugs when he was
going to college, and that his father was convicted of petty theft and went to
prison for two years before he was born. So it's easy to see that anything he
says is worthless, and we don't need to listen to anything from him."
