A document that describes the objectives and purpose(s) of the research, the questions to be answered, the methodologies to be employed.
Research proposals usually address what a person/business/team want to accomplish, why they want to continue and how they are going to accomplish it?
A research proposal is most commonly intended as a document to gain the confidence of others with the promise behind the research and that the creators of the document are competent with the knowledge and capacity to move forward with it.