actinium

A1C3T1I1N1I1U1M3
/ækˈtɪniəm/

noun

A radioactive, metallic chemical element (symbol: Ac) with an atomic number of 89; found in uranium ores.

Similar
Acatomic number 89
OriginFrench actinium ← Ancient Greek ᾰ̓κτῑ́ς (ăktī́s) →
UncommonScrabble 12
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Meanings

nounactinium (usually uncountable, plural actiniums)

plural actiniums

  1. uncountableusuallychemistryA radioactive, metallic chemical element (symbol: Ac) with an atomic number of 89; found in uranium ores.
    1. countableusuallychemistryAn atom of this element.

Synonyms & antonyms

nouna radioactive element of the actinide series; found in uranium ores

Similar
Acatomic number 89
Broader
chemical elementelement
Also see
ac

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

  1. Ancient Greekᾰ̓κτῑ́ς (ăktī́s)
  2. Frenchactino-
  3. Frenchactinium
  4. Englishactinium

Borrowed from French actinium. actin- + -ium.

More words from French

Full word history & related roots →

Translations

Afrikaans aktinium
  • aktiniumchemical element
Arabic أَكْتِينِيُوم
  • أَكْتِينِيُوم (ʔaktīniyūm)chemical element
Basque aktinioa
  • aktinioachemical element
Bulgarian актиний
  • актиний (aktinij)chemical element
Catalan actini
  • actinichemical element
Chinese Mandarin 錒 /锕
  • 錒 /锕 (ā)chemical element
Czech aktinium
  • aktiniumchemical element
Danish actinium
  • actiniumchemical element
Dutch actinium
  • actiniumchemical element
Esperanto aktinio
  • aktiniochemical element
Estonian aktiinium
  • aktiiniumchemical element
Finnish aktinium
  • aktiniumchemical element
French actinium
  • actiniumchemical element
German Actinium
  • Actiniumchemical element
Greek ακτίνιο
  • ακτίνιο (aktínio)chemical element
Hebrew אַקְטִינְיוּם
  • אַקְטִינְיוּם (aktínyum)chemical element
Hindi एक्टिनियम, एजातु
  • एक्टिनियम (ekṭiniyam)chemical element
  • एजातु (ejātu)chemical element
Hungarian aktínium
  • aktíniumchemical element
Icelandic aktín
  • aktínchemical element
Irish achtainiam
  • achtainiamchemical element
Italian attinio
  • attiniochemical element
Japanese アクチニウム
  • アクチニウム (akuchiniumu)chemical element
Korean 악티늄
  • 악티늄 (aktinyum)chemical element
Latin actinium
  • actiniumchemical element
Latvian aktīnijs
  • aktīnijschemical element
Lithuanian aktinis
  • aktinischemical element
Malay aktinium
  • aktiniumchemical element
Norwegian Bokmål actinium
  • actiniumchemical element
Persian اکتینیم
  • اکتینیم (aktiniyom)chemical element
Polish aktyn
  • aktynchemical element
Portuguese actínio
  • actíniochemical element
Romanian actiniu
  • actiniuchemical element
Russian акти́ний
  • акти́ний (aktínij)chemical element
Scottish Gaelic aictiniam
  • aictiniamchemical element
Slovak aktínium
  • aktíniumchemical element
Spanish actinio
  • actiniochemical element
Swedish aktinium
  • aktiniumchemical element
Tamil அக்டினியம்
  • அக்டினியம் (akṭiṉiyam)chemical element
Thai แอกทิเนียม
  • แอกทิเนียม (ɛ́k-tí-nîiam)chemical element
Turkish aktinyum
  • aktinyumchemical element
Ukrainian акти́ній
  • акти́ній (aktýnij)chemical element
Urdu عیکٹنیئم
  • عیکٹنیئمchemical element
Vietnamese actini
  • actinichemical element
Welsh actiniwm
  • actiniwmchemical element
Cite this entry
APA

actinium. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/actinium

MLA

“actinium.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/actinium. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “actinium,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/actinium.

Source: actinium on Wiktionary, CC BY-SA 4.0.