noun
: a philatelic cover bearing postal markings showing that it was mailed on a first day at a first-day city and that its stamp belongs to the new issue of that first day
noun
: a philatelic cover bearing postal markings showing that it was mailed on a first day at a first-day city and that its stamp belongs to the new issue of that first day
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012