A ring- or donut-shaped area or structure.
The ring of the sun not covered by the moon in an annular solar eclipse.
Structure in a fern that consists of differentially thick-walled cells on a sporangium that bend and distort as a result of drying.
The region in a plane between two concentric circles of different radii.
The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.
The space contained between the centre well bore and any external tubing. Sometimes used for separated gas flow.
Any topological space homeomorphic to the region in a plane between two concentric circles of different radius.
An edge that begins and ends on the same vertex.
A complete circuit for an electric current.
A quasigroup with an identity element.
A ring road or beltway.
The opening so formed.
A loop-shaped intrauterine device.
A small, narrow opening; a loophole.
A flexible region in a protein's secondary structure.
A place at a terminus where trains or trams can turn round and go back the other way without having to reverse; a balloon loop, turning loop, or reversing loop.
An aerobatic maneuver in which an aircraft flies a circular path in a vertical plane.
An endless strip of tape or film allowing continuous repetition.
A length of thread, line or rope that is doubled over to make an opening.
A shape produced by a curve that bends around and crosses itself.
A programmed sequence of instructions that is repeated until or while a particular condition is satisfied.
A path that starts and ends at the same point.
A bus or rail route, walking route, etc. that starts and ends at the same point.
To move in a loop.
To move something in a loop.
To place in a loop.
To join electrical components to complete a circuit.
To fly an aircraft in a loop.
To duplicate the route of a pipeline.
To form something into a loop.
To create an error in a computer program so that it runs in an endless loop and the computer freezes up.
To fasten or encircle something with a loop.
To form a loop.