What is Ad Quem?

Legal Definition
A Latin expression which signifies to which, in the computation of time or distance, as the day ad quem. The last day of the term, is always computed. See A quo.
-- Bouviers Law Dictionary
Legal Definition
To which. A term used in the computation of time or distance, as correlative to a quo; denotes the end or terminal point. See A Quo.
-- Black's Law Dictionary
Legal Definition
To which.
-- Ballentine's Law Dictionary