Researcher's aid: Abbr

• Check in the mail?: Abbr
• Letters in a letter
• Env. insertion
• In the envelope: abbr
• Business letter abbr.
• What a SASA is
• Ref. set
• Invoice, e.g.: Abbr
• Envelope contents: Abbr

Wiktionary Word definitions in Wiktionary
abbr. enclosure (qualifier indicating that a letter is accompanied by further material English)