actinide
/ˈæktɪnaɪd/noun
actinide is a noun meaning “Any of the 15 radioactive elements of the periodic table from actinium to lawrencium that are positioned under the lanthanides, to which they have…” (English Wiktionary, September 2026). It is spelled A-C-T-I-N-I-D-E and has 3 syllables, and it appears about once in every 12 million words in written English (wordfreq, 2021 data). The plural of actinide is actinides.
What does actinide mean?
noun
- 1
Any of the 15 radioactive elements of the periodic table from actinium to lawrencium that are positioned under the lanthanides, to which they have similar chemistry.
- 2
Any of the 14 elements from actinium to nobelium (lawrencium is excluded by some authors as it is a d-block rather than an f-block element).
- 3
datedAny of the 14 elements from thorium to lawrencium (actinium having been mistakenly excluded because it was thought to be a d-block element in the past).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How do you pronounce actinide?
- /ˈæktɪnaɪd/
Actinide has 3 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-actinide.wav, Wikimedia Commons (author and licence on each file's page).
Forms of actinide
- actinides plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How common is actinide?
Actinide appears about once in every 12 million words in written English, the 105,204th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Actinide in Spanish, French, German and Portuguese
In the sense one of a group of radioactive elements:
| Language | Words |
|---|---|
| German | Actiniden |
| Spanish | actínido |
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does actinide come from?
From actin- + -ide.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).