Toroidal

Toroidal describes something which resembles or relates to a torus or toroid:

Mathematics

Toroidal coordinates, a three-dimensional orthogonal coordinate system
Toroidal and poloidal coordinates, directions for a three-dimensional system which follows a circular ring around the surface
Toroidal graph, a graph whose vertices can be placed on a torus such that no edges cross
Toroidal grid network, an n-dimensional grid connected circularly in more than one dimension
Toroidal polyhedron, partition of a toroidal surface into polygons

Toroidal engine, an internal combustion engine with pistons that rotate inside a ring-shaped cylinder
Toroidal expansion joint, a metallic assembly consisting of a series of circular tubes used in high pressure applications
Toroidal inductors and transformers, a type of electrical device using magnetic cores with a ring or donut shape
Toroidal propeller, a loop-shaped propeller used in aviation and maritime transport
Toroidal reflector, a reflector whose surface is a section of a torus which has a different focal distance depending on the angle of the mirror

Toroidal planet, planet in the shape of a toroidal or doughnut shape
Toroidal ring model in theoretical physics
Toroidal solenoid, 1946 design for a fusion power device
Vortex ring, also known as a toroidal vortex; a toroidal flow in fluid mechanics