Meaning
Ad hominem, to the man, in logic, an argument, adapted to touch the prejudices of the person addressed.
Ad inquirendum, in law, a judicial writ commanding inquiry to be made.
Ad libitum [L.] at pleasure
Ad valorem, according to the value, in commerce and finance, terms used to denote duties or charges laid upon goods, at a certain rate per cent, upon their value, as stated in their invoices; in opposition to a specific sum upon a given quantity or number.