This page gathers the 757 dictionary entries belonging to the domain “Geometry”, as labelled by Wiktionary. Each word leads to its full entry: definitions, etymology, pronunciation, examples. Page 8 of 8: from “trapezoid” to “zonohedron”.
- trapezoid noun A (convex) quadrilateral with two (non-adjacent) parallel sides.
- traverse noun A line lying across a figure or other lines; a transversal.
- triakis icosahedron noun A Catalan solid with 60 isosceles triangle faces, 90 edges and 32 vertices, being the dual of the truncated dodecahedron.
- triakis octahedron noun A Catalan solid with 24 isosceles triangle faces, 36 edges and 14 vertices, being the dual of the truncated cube.
- triangle noun A polygon with three sides and three angles.
- triangle postulate noun An axiom that states that the sum of the angles in a triangle equals two right angles, equivalent to the parallel postulate.
- triangular hebesphenorotunda noun A polyhedron, one of the Johnson solids, whose faces are composed of 13 triangles, 3 squares, 3 pentagons, and 1 hexagon.
- triangulate verb To divide into triangles.
- triangulation noun A subdivision of a planar object into triangles, and by extension the subdivision of a higher-dimension geometric object into simplices.
- trident noun A curve of third order of the form
- trigon noun A triangle.
- trigonometry noun The branch of mathematics that deals with the relationships between the sides and angles of (in particular) right-angled triangles, as…
- trihexagonal adj Pertaining to a semiregular tiling of the Euclidean plane with two triangles and two hexagons alternating on each vertex.
- trilobular adj Having a shape that is broadly triangular but is rounded, with three lobular segments conjoined.
- trisection noun The act of division of something (such as an angle, line segment, or circle) into three parts, especially three equal parts.
- trisector noun A line or curve that trisects something.
- trisoctahedron noun triakis octahedron
- trochoid noun The curve traced by a point on a circle as it rolls along a straight line
- trope noun A tangent space meeting a quartic surface in a conic.
- truncate verb To replace a corner by a plane (or to make a similar change to a crystal).
- truncated cube noun A polyhedron with eight triangular and six octagonal faces that is an Archimedean solid and can be constructed by truncating a cube at each…
- truncated cuboctahedron noun An Archimedean solid that is isogonal and has twenty-six regular faces (twelve square, eight hexagonal and six octagonal); a great…
- truncated dodecahedron noun An Archimedean solid with thirty-two regular faces (twelve decagons and twenty triangles) and ninety edges.
- truncated icosahedron noun A polyhedron that has thirty-two faces (12 regular pentagons and 20 regular hexagons) and 60 vertices and 90 edges, and is one of the…
- truncated tetrahedron noun A convex polyhedron, with four triangular and four hexagonal faces, that is an Archimedean solid and can be constructed by truncating a…
- truncation noun An operation in any dimension that cuts a regular polytope at its vertices, creating a new facet in place of each vertex.
- truncus noun A curve in the Cartesian plane consisting of all points (x,y) satisfying an equation of the form f(x)=a/(x+b)²+c where a, b, and c are…
- Tschirnhausen cubic noun A plane curve defined, in its left-opening form, by the polar equation r=a sec ³(θ/3) where sec is the secant function.
- turn noun A unit of plane angle measurement based on this movement.
- turning number noun A version of winding number in which the number of rotations is counted with respect to the tangent of the curve rather than a fixed point.
- umbilic noun An umbilicus.
- umbilicus noun One of the foci of an ellipse or other curve.
- ungula noun A section of a cylinder, cone, or other solid of revolution, cut off by a plane oblique to the base; so called from its resemblance to the…
- uniform adj (of a polyhedron) That is isogonal and whose faces are regular polygons; (of an n-dimensional (n>3) polytope) that is isogonal and whose…
- valence noun For a correspondence T on a curve: a number k such that the divisors T(P)+kP are all linearly equivalent.
- valency noun Alternative form of valence.
- vanishing ideal noun An ideal consisting of all polynomials (belonging to a certain polynomial ring) which zero out within a given algebraic variety.
- variety noun Ellipsis of algebraic variety (“the set of solutions of a given system of polynomial equations over the real or complex numbers; any of…
- Varignon parallelogram noun The parallelogram involved in Varignon's theorem, whose corners are the midpoints of the sides of an arbitrary quadrilateral.
- vector space noun A set of elements called vectors, together with some field and operations called addition (mapping two vectors to a vector) and scalar…
- vertex noun The common point of the two rays that form an angle.
- vertical angle noun Any of the opposite angles formed by intersecting lines.
- vinculum noun A horizontal line drawn over two letters to denote the line segment joining them.
- visual angle noun The angle formed by two rays of light, or two straight lines drawn from the extreme points of an object to the center of the eye.
- Weaire-Phelan structure noun A three-dimensional structure representing an idealized foam of equal-sized bubbles, with two different shapes.
- wedge noun A five-sided polyhedron with a rectangular base, two rectangular or trapezoidal sides meeting in an edge, and two triangular ends.
- witch noun A certain curve of the third order, described by Maria Agnesi under the name versiera.
- Witt group noun given a variety X, the quotient of the Grothendieck group of isometry classes of quadratic spaces on X, with respect to orthogonal sum…
- x-axis noun The axis on a graph that is usually drawn left to right and usually shows the range of values of an independent variable.
- y-axis noun The axis on a graph that is usually drawn from bottom to top and usually shows the range of values of variable dependent on one other…
- z-axis noun The axis on a graph of at least three dimensions that is usually drawn vertically and usually shows the range of values of a variable…
- Zariski topology noun Originally, a topology applicable to algebraic varieties, such that the closed sets are the variety's algebraic subvarieties; later, a…
- Zariski-Riemann space noun A locally ringed space of a subring k of a field K, whose points are valuation rings containing k and contained in K. They generalize the…
- zero locus noun The set of points (usually in affine or projective space, but more generally in the domain of the function) where the given polynomial (or…
- zero-dimensional adj Having zero dimensions; having no extent in any direction.
- zone noun The curved surface of a frustum of a sphere, the portion of surface of a sphere delimited by parallel planes.
- zonohedron noun A special case of convex polyhedron, in which every face of the polyhedron is a polygon with point symmetry.