An unwritten agreement can also be referred to as an implied agreement, informal agreement, or verbal agreement. These terms all describe an agreement that has been made without a formal written contract. Other possible synonyms for "unwritten agreement" include a handshake agreement, gentlemen's agreement, or tacit understanding. These agreements often rely on trust and mutual understanding rather than a legal contract. However, despite the lack of a written document, they are still enforceable under certain circumstances. It is important to be clear about the terms of any agreement, whether written or unwritten, to avoid miscommunication or misunderstandings.