filament

plural filaments

1. A fine thread or wire.
2. Such a wire, as can be heated until it glows, in an incandescent light bulb or a thermionic valve.

   Lighting was unimaginative for the standard stock with naked tungsten filament bulbs and metal reflectors. However, all compartments had individual reading lights above the seats with attractive glass shades.

   1979 August, Graham Burtenshaw, Michael S. Welch, “O.V.S. Bulleid's SR loco-hauled coaches - 1”, in Railway World, page 398

3. astronomyA massive, thread-like structure, such as those gaseous ones which extend outward from the surface of the sun, or such as those (much larger) ones which form the boundaries between large voids in the universe.

   solar filament

   2 more examples

   galaxy filament

   the Ursa Major Filament

4. biologyThe stalk of a flower stamen, supporting the anther.
5. businessA continuous object, limited in length only by its spool, and not cut to length.
   1. 3D printingbusinessA spool of plastic used as a material for 3D-printed objects.