Русско-англо-русский юридический словарь

A letter of intent (LOI or LoI, and sometimes capitalized as Letter of Intent in legal writing, but only when referring to a specific document under discussion) is a document outlining an agreement between two or more parties before the agreement is finalized. Such agreements may be Asset Purchase Agreements, Share Purchase Agreements, Joint-Venture Agreements, Lease Agreements, and overall all Agreements which aim at closing a financially large deal. (Wikipedia)

In commercial practice, particularly when transactions of considerable complexity are involved, it is quite frequent that after prolonged negotiations the parties sign an informal document called “Preliminary Agreement”, “Memorandum of Understanding”, “Letter of Intent” or the like, containing the terms of the agreement so far reached, but at the same time state their intention to provide for the execution of a formal document at a later stage (“Subject to Contract”, “Formal Agreement to follow”). (UNIDROIT PRINCIPLES 2010)