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

• bristle
• fiber
• hair
• 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

These results were possible thanks to an innovative technique involving Chandra data that allows hot filaments to be distinguished from other structures. —Robert Lea, Space.com, 29 Jan. 2025

Instead, the fungi’s mycelium–the underground network of filaments similar to plant roots that absorb nutrients–is the most bioluminescent. —Laura Baisas, Popular Science, 9 Jan. 2025

Day 23 of the 2024 Space Telescope Advent Calendar: a spray of glowing filaments. —Alan Taylor, The Atlantic, 23 Dec. 2024

But the team is still unsure how the filaments formed in the first place. —Ashley Strickland, CNN, 30 Oct. 2024

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

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