noun · 2 senses · updated from the 2026-07-25 local source snapshot
Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.
Sound
Pronunciation
Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.
thôr'ēəm
/ˈθɔːɹiəm/
US:Recorded audio is listed in the source snapshot.
General-American:Recorded audio is listed in the source snapshot.
rhymes with -ɔːɹiəm
CMU ARPABET:TH AA1 R IY0 AH0 M
Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.
1
noun
Meaning 1
A chemical element (symbol Th) with atomic number 90. A weakly radioactive, malleable, moderately hard silvery metal that tarnishes black when exposed to air.
Definition source: English Wiktionary via Wiktextract
Usage: uncountable, usually
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
2
noun
Meaning 2
a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands
Definition source: Princeton WordNet 3.0
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: Th, atomic number 90
Antonyms: none provided
Broader terms: metallic element, metal
Narrower terms: thorium-228, radiothorium
History
Etymology
Etymology tree English Thor Proto-Indo-European *-om Proto-Italic *-om Latin -umder. English -ium English thorium From Thor + -ium.
Across languages
Translations
72 source translations are retained for this English entry.
