Is it ensure, insure, or assure?
musical instrument in which the soundboard and plane of the strings run vertically, perpendicular to the keyboard, thus taking up less floor space than the normal grand piano. Upright pianos are made in various heights; the shortest are called spinets or consoles, and these are generally considered to have an inferior tone resulting from the shortness of their strings and their relatively small soundboards. The larger upright pianos were quite popular in the later 19th and early 20th centuries. The action (hammer and damper mechanism) of the upright differs from the grand-piano action mainly in that upright action is returned to a resting position by means of springs rather than by gravity alone, as in a grand. This, in part, accounts for the characteristic "touch" of uprights, which is distinct from that of grands. The chief advantages of upright pianos lie in their modest price and compactness; they are instruments for the home and school, not for the concert stage