Pronunciation IPA (key): /ˈfɪləmənt/ Audio (UK)(file) Noun Singular filament Plural filaments (countable) A filament is a fine wire that can be heated until it glows (countable) (physics) (astronomy) A filament is a thread-like structure that extends outward from the surface of the sun. (countable) (botany) A filament is the stalk of a flower stamen that supports the anther.Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads