filament

noun

fil·​a·​ment ˈfi-lə-mənt 

: a single thread or a thin flexible threadlike object, process, or appendage (see appendage sense 2): such as

a

: a tenuous (see tenuous sense 2) conductor (as of carbon or metal) made incandescent by the passage of an electric current

specifically : a cathode (see cathode sense 2) in the form of a metal wire in an electron tube

b(1)

: a thin and fine elongated constituent part of a gill (see gill entry 2 sense 1)

(2)

: an elongated thin series of cells attached one to another or a very long thin cylindrical single cell (as of some algae, fungi, or bacteria)

c

: the anther-bearing stalk of a stamen see flower illustration

filamentary

ˌfi-lə-ˈmen-t(ə-)rē 

adjective

filamentous

ˌfi-lə-ˈmen-təs 

adjective

Synonyms of filament

• fiber
• wire
• thread

Examples of filament in a Sentence

algae covered with tiny filaments

the cable was made up of fine filaments twisted together

Recent Examples on the Web

FibreSeek's spools of 500-m (1,640-ft) carbon fiber filament can be had at $39 each through the campaign, which is 20% below its MSRP. —New Atlas, 11 Dec. 2025

Kipaş Textiles will then turn these into certified, high-quality filament yarns and staple fibers for new textile collections. —Angela Velasquez, Sourcing Journal, 10 Dec. 2025

They're created at Swellcycle with just enough bioplastic filament called polylactic acid. —Molly McCrea, CBS News, 5 Dec. 2025

That flows of material along cosmic filaments can influence the properties of galaxies to this degree is a surprise though, and will lead to important modifications in models of how galaxies form. —Keith Cooper, Space.com, 4 Dec. 2025

Word History

Etymology

Middle French, from Medieval Latin filamentum, from Late Latin filare to spin — more at file

First Known Use

1594, in the meaning defined above

Rhymes for filament

• monofilament

Kids Definition

filament

noun

fil·​a·​ment ˈfil-ə-mənt 

: a single thread or a thin flexible threadlike object, process, or part: as

a

: a wire (as in a light bulb) that is made to glow by the passage of an electric current

b

: a long chain of cells (as of some bacteria or algae)

c

: the anther-bearing stalk of a plant stamen

filamentous

ˌfil-ə-ˈment-əs 

adjective

Medical Definition

filament

noun

fil·​a·​ment ˈfil-ə-mənt 

: a single thread or a thin flexible threadlike object, process, or appendage

especially : an elongated thin series of cells attached one to another or a very long thin cylindrical single cell (as of some algae, fungi, or bacteria)

filamentous

ˌfil-ə-ˈment-əs 

adjective