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.
  3. A 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
    galaxy filament
    the Ursa Major Filament
  4. The stalk of a stamen in a flower, supporting the anther.
  5. A continuous object, limited in length only by its spool, and not cut to length.

The above text is a snippet from Wiktionary: filament
and as such is available under the Creative Commons Attribution/Share-Alike License.

Need help with a clue?
Try your search in the crossword dictionary!