[fil-uh-muh nt]
See more synonyms for filament on
  1. a very fine thread or threadlike structure; a fiber or fibril: filaments of gold.
  2. a single fibril of natural or synthetic textile fiber, of indefinite length, sometimes several miles long.
  3. a long slender cell or series of attached cells, as in some algae and fungi.
  4. Botany. the stalklike portion of a stamen, supporting the anther.
  5. Ornithology. the barb of a down feather.
  6. (in a light bulb or other incandescent lamp) the threadlike conductor, often of tungsten, in the bulb that is heated to incandescence by the passage of current.
  7. Electronics. the heating element (sometimes also acting as a cathode) of a vacuum tube, resembling the filament in an incandescent bulb.
  8. Astronomy. a solar prominence, as viewed within the sun's limb.

Origin of filament

1585–95; < New Latin fīlāmentum, equivalent to Late Latin fīlā(re) to wind thread, spin (see file1) + Latin -mentum -ment
Related formsfil·a·ment·ed, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for filament

fiber, thread, hair, wire, stalk, tendril, strand

Examples from the Web for filament

Contemporary Examples of filament

Historical Examples of filament

  • The filament current of an audion-bulb averages about one ampere.

  • Close to the filament is a graphite disk which serves as one of the electrodes.

  • She had no remains of tenderness left for him: not a filament.

    Love and Lucy

    Maurice Henry Hewlett

  • There is no oxygen to combine with the filament; so the lamp does not burn out.

    Common Science

    Carleton W. Washburne

  • When the filament breaks, an electric lamp will no longer glow.

    Common Science

    Carleton W. Washburne

British Dictionary definitions for filament


  1. the thin wire, usually tungsten, inside a light bulb that emits light when heated to incandescence by an electric current
  2. electronics a high-resistance wire or ribbon, forming the cathode in some valves
  3. a single strand of a natural or synthetic fibre; fibril
  4. botany
    1. the stalk of a stamen
    2. any of the long slender chains of cells into which some algae and fungi are divided
  5. ornithol the barb of a down feather
  6. anatomy any slender structure or part, such as the tail of a spermatozoon; filum
  7. astronomy
    1. a long structure of relatively cool material in the solar corona
    2. a long large-scale cluster of galaxies
Derived Formsfilamentary (ˌfɪləˈmɛntərɪ, -trɪ) or filamentous, adjective

Word Origin for filament

C16: from New Latin fīlāmentum, from Medieval Latin fīlāre to spin, from Latin fīlum thread
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for filament

1590s, from Modern Latin filamentum, from Late Latin filare "to spin, draw out in a long line," from Latin filum "thread" (see file (v.)).

Online Etymology Dictionary, © 2010 Douglas Harper

filament in Medicine


  1. A fibril, fine fiber, or threadlike structure.
Related formsfil′a•mentous (-mĕntəs) null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

filament in Science


  1. A fine or slender thread, wire, or fiber.
  2. The part of a stamen that supports the anther of a flower; the stalk of a stamen. See more at flower.
    1. A fine wire that gives off radiation when an electric current is passed through it, usually to provide light, as in an incandescent bulb, or to provide heat, as in a vacuum tube.
    2. A wire that acts as the cathode in some electron tubes when it is heated with an electric current.
  3. Any of the dark, sinuous lines visible through certain filters on the disk of the Sun. Filaments are solar prominences that are viewed against the solar surface rather than being silhouetted along the outer edges of the disk. See more at prominence.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.