1st-class mail

Definitions of 1st-class mail
  1. noun
    mail that includes letters and postcards and packages sealed against inspection
    synonyms: 1st class, first class, first-class mail
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    types:
    correspondence
    communication by the exchange of letters
    card
    a rectangular piece of stiff paper used to send messages (may have printed greetings or pictures)
    type of:
    mail
    the bags of letters and packages that are transported by the postal service
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