Query, Query Letter (N)
(1) a one page letter to an editor pitching a proposed non-fiction article.
(2) a pitch to a director for a screenplay.
(3) a letter to an editor for a novel usually accompanied with a synopsis and sample chapters.
A query letter "pitches" an article or book idea to an editor to see if that editor might be interested in purchasing the proposed or completed manuscript.
An inquiry from a writer to an editor of a magazine, newspaper, etc., regarding the acceptability of or interest in an idea for an article, news story, or the like: usually presented in the form of a letter that outlines or describes the projected piece.
The act of writing and submitting a query letter.
Source: Brian Westover