unsustainable
adjective, noun
unsustainable is spelled U-N-S-U-S-T-A-I-N-A-B-L-E: 13 letters and 5 syllables. It appears 1.4 times per million words in written English, the 23,835th most frequent word form (wordfreq, 2021 data). As an adjective, unsustainable means “Not sustainable” (English Wiktionary, September 2026).
How many letters and syllables are in unsustainable?
| Letters | 13: U-N-S-U-S-T-A-I-N-A-B-L-E |
|---|---|
| Syllables | 5 (from its American pronunciation) |
| In writing | 1.4 times per million words; the 23,835th most frequent word form |
| Wrong spellings searched | none measured in search |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How common is unsustainable?
Unsustainable appears 1.4 times per million words in written English, the 23,835th 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).
How do you pronounce unsustainable?
Unsustainable has 5 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-unsustainable.wav, Wikimedia Commons (author and licence on each file's page).
Forms of unsustainable
- more unsustainable comparative
- most unsustainable superlative
- unsustainables plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does unsustainable mean?
The meanings the English Wiktionary records, quoted as written there (source below).
adjective
- 1
Not sustainable.
noun
- 1
Something that cannot be sustained.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Unsustainable in Spanish, French, German and Portuguese
In the sense Not sustainable:
| Language | Words |
|---|---|
| French | pas viable, non viable, pas tenable, intenable, insoutenable |
| German | unhaltbar |
| Portuguese | insustentável |
| Spanish | insostenible |
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 unsustainable come from?
From un- + sustainable.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).