undecidable
adjective
undecidable is spelled U-N-D-E-C-I-D-A-B-L-E: 11 letters. It appears about once in every 16 million words in written English, the 121,279th most frequent word form (wordfreq, 2021 data). As an adjective, undecidable means “Incapable of being algorithmically decided in finite time. For example, a set of strings is undecidable if it is impossible to program a computer…” (English Wiktionary, September 2026).
How many letters and syllables are in undecidable?
| Letters | 11: U-N-D-E-C-I-D-A-B-L-E |
|---|---|
| In writing | about once in every 16 million words; the 121,279th most frequent word form |
| Wrong spellings searched | none measured in search |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How common is undecidable?
Undecidable appears about once in every 16 million words in written English, the 121,279th 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 undecidable?
- US
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-us-undecidable.ogg, Wikimedia Commons (author and licence on each file's page).
What does undecidable mean?
The meanings the English Wiktionary records, quoted as written there (source below).
adjective
- 1
Incapable of being algorithmically decided in finite time. For example, a set of strings is undecidable if it is impossible to program a computer (even one with infinite memory) to determine whether or not specified strings are included.
- 2
(of a WFF) logically independent from the axioms of a given theory; i.e., that it can never be either proved or disproved (i.e., have its negation proved) on the basis of the axioms of the given theory. (Note: this latter definition is independent of any time bounds or computability issues, i.e., more Platonic.)
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Undecidable in Spanish, French, German and Portuguese
In the sense incapable of being algorithmically decided:
| Language | Words |
|---|---|
| German | unentscheidbar |
| Spanish | indecidible |
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 undecidable come from?
From un- + decidable.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).