Originally: a triangle in which one of the angles is obtuse. In later use sometimes also: any geometric figure in which one or more of the angles…

Geometry. An oblique-angled figure. Obsolete. rare.

Made up or composed of triangles. (In later use in Natural History) †Also as n. a figure made up of triangles (obsolete).

A figure bounded by a semicircle and two concave quadrants (all having the same radius), which roughly resembles the blade of a battleaxe.

Geometry. A loop formed by a curve, esp. that of a strophoid. Cf. foliate, adj. 2b. Now rare.

Oblong form.

Geometry. A figure of six lines.

a figure or design made up of a number of points.

Geometry. The figure composed of four straight lines in a plane and their six points of intersection: commonly called complete quadrilateral.

The complete figure composed of four points in a plane and their six connecting straight lines; commonly called complete quadrangle.

Geometry, etc. A set of three lines; spec. the figure formed by three straight lines in one plane not intersecting in the same point; also more…

Any of the five distinct planar shapes that can be formed by joining four identical squares by their edges.

Any planar shape formed by joining three identical squares by their edges.

a polyabolo composed of four triangles.

attributive. Designating or relating to (a) a tiling of a plane using a finite number of tile shapes according to certain constraints (such that no…