noun
: a package of fourth-class mail to the outside of which is affixed a letter or other piece of first-class mail matter — used in the United States postal system
noun
: a package of fourth-class mail to the outside of which is affixed a letter or other piece of first-class mail matter — used in the United States postal system
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012