class of mail offered by the U.S. Postal Service for parcels that weigh more than 12 ounces, up to 70 pounds; combined length and girth must not exceed 108 inches. The most expeditious method of shipping is used on Priority Mail; two-day service is generally provided but not guaranteed. Letter mail may also be expedited by being sent Priority Mail; the minimum rate (which covers letters and parcels up to one pound) is currently $4.05.
expedited two-day delivery service provided by the U.S. Postal Service for mail that would otherwise mail First Class, Standard Mail, or Periodicals class. Priority mail costs less than half the amount charged by most overnight delivery services. The USPS provides envelopes and boxes for priority mail at no charge.
