A formal invitation containing a scope of work which seeks a formal response (proposal) describing both methodology and compensation to form the basis of a contract.
(Wideman Comparative Glossary of Common Project Management Terms v2.1)
Other Definitions
Request For Proposal – A document prepared by the customer to solicit proposals from potential providers. The Request For Proposal consists of a Solicitation Letter, Instructions to Bidders, Evaluation Criteria,Statement of Work, and a System Specification. The provider issues an RFP to potential subcontractors.
(Wideman Comparative Glossary of Common Project Management Terms v2.1)