Postal

1. Belonging to the post office or mail service; as, postal arrangements; postal authorities.
   
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.