n. A shed or sloping roof projecting from a main wall or the side or end of a building, and sometimes constructed over a door or window to protect it from the weather; an appentice. See also cut under appentice.n. Anything resembling a penthouse, or occupying the same relative position with regard to something else.To provide with a penthouse or sloping roof; shelter or protect by means of a shed sloping from the wall, or of something resembling it.n. In artillery, a frame structure sometimes used to protect a sea-coast gun-carriage from continuous severe weather: so made that it can quickly be put in place or removed.