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

Throw on an oversize black pantsuit, add a filament-thin chain at the waist and let your untucked shirt, trimmed with a random assortment of little baubles, peek out at the bottom. — Vanessa Friedman, New York Times, 4 Oct. 2026

The New Zealand company’s process drafts wool around a high-performance filament without the twist used in conventional ring spinning. — Alexandra Harrell, Footwear News, 2 Oct. 2026

This generated a narrow conducting filament inside the insulating film. — Georgina Jedikovska, Interesting Engineering, 2 Oct. 2026

The filament bulb’s lurid orange-yellow was different — not less orange or yellow, but somehow also whiter, richer, rounder, as if Sorolla had worked in some of his cadmium hues. — Zain Khalid, Vulture, 1 Oct. 2026

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