x_{1} is a frustum/cone/cylinder/pyramid made of material x_{2} with larger base x_{3} and at-most-as-large base x_{4}, with other characteristics x_{5}.

x_{4} cannot be larger in hyperarea than x_{3}. A cone and a pyramid are degenerate frusta with exactly one base (x_{4}) being exactly a point (the apex); a line segment is a doubly-degenerate frustum with x_{3} (and therefore x_{4}) being a point. The bases should typically be approximately parallel to one another; they need not be perpendicular to their axis. Except possibly when at least one base is a point, they will be (apprpximately) geometrically similar to one another (having the same cross-section along parallel planes wrt the axis, modulo scale/size, which will nonetheless be multiplied by a uniform factor in all 'dimensions'). A round base will produce, approximately, a circular cone or a (circular) cylinder.

- tarmrsilondre
- x
_{1}is a generalized cylinder (see notes for details) of form/shape x_{2}.