\Post"al\, a. [Cf. F. postal.]
Belonging to the post office or mail service; as, postal
arrangements; postal authorities.
{Postal card}, or {Post card}, a card sold by the government
   for transmission through the mails, at a lower rate of
   postage than a sealed letter. The message is written on
   one side of the card, and the direction on the other.
{Postal money order}. See {Money order}, under {Money}.
{Postal note}, an order payable to bearer, for a sum of money
   (in the United States less than five dollars under
   existing law), issued from one post office and payable at
   another specified office.
{Postal Union}, a union for postal purposes entered into by
   the most important powers, or governments, which have
   agreed to transport mail matter through their several
   territories at a stipulated rate.