A final letter sent by a creditor or its solicitors, following a series of demands for payment etc. or negotiations which sets a timescale (e.g. seven days) within which satisfaction is required and failing such a response, legal proceedings are to follow e.g. commencing winding up proceedings. Such a letter should not be sent casually and without intent to put it into effect or else your credibility may suffer!
Easyform Glossary of Law Terms. — UK law terms.