Columns of justified lines of text that taper towards the bottom. Explored by early printers in the printing of incunabula and revived by William Morris in the Arts and Crafts movement [Haslam] Other terms include in pendentive and half-diamond indentation [Campbell] Known in French as cul-de-lampe (also used for the ornament placed at the end of a chapter) and in German as Spitzkolumne (also used, by extension, for any page at the end of a chapter that is left partly blank).
See also the terms Berkemeyer, Rummer, and (knotted) triangle as used by Goran Proot for specific paragraph styles, in reference to the shapes of drinking glasses.