Sentence:  This theorem holds good for complete solids as well as <WSD>frustums</WSD>, whether right or oblique, and not only of the solids generated from the conic sections, but also of all pyramids, cones, and in short of any solid, whose parallel sections are similar figures. 
Meaning of the word marked with <WSD> tags:  A cone or pyramid whose tip has been truncated by a plane parallel to its base.