Old English seofon, of Germanic origin; related to Dutch zeven and German sieben, from an Indo-European root shared by Latin septem and Greek hepta .

seofonfeald

sevenfold

Feald (plural Fealder)

field

A pulsating magnetic field is produced, when the stator winding of the single-phase induction motor shown below is energised by a single phase supply. The word Pulsating means that the field builds up in one direction falls to zero and then builds up in the opposite direction.

In knot theory, the 7 knot, also known as the septoil knot, the septafoil knot, or the (7, 2)-torus knot, is one of seven prime knots with crossing number seven.