Wiktionary
queen post
n. A supporting post designed to span longer openings than a king post.
WordNet
queen post
n. vertical tie post in a roof truss
Wikipedia
Queen post
A queen post is a tension member in a truss that can span longer openings than a king post truss. A king post uses one central supporting post, whereas the queen post truss uses two. Even though it is a tension member, rather than a compression member, they are commonly still called a post. A queen post is often confused with a queen strut, one of two compression members in roof framing which do not form a truss in the engineering sense.