from
The Collaborative International Dictionary of English v.0.48
Postal \Post"al\, a. [Cf. F. postal.]
Belonging to the post office or mail service; as, postal
arrangements; postal authorities.
[1913 Webster]
{Postal card}, or {Post card}, a card used for transmission
of messages through the mails, at a lower rate of postage
than a sealed letter; also called {postcard}. Such cards
are sold by the government with postage already paid, or
by private vendors without a postage stamp. The message is
written on one side of the card, and the address 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.
[1913 Webster]