isothermal
"isothermal" is a 10-letter English headword indexed on PlainSpell.
The verdict
“isothermal” is uncommon English (frequency #65,221 among 17,902 “I” headwords), classed as an adjective. The kind of spelling people second-guess.
- #65,221
- frequency rank, English
- 17,902
- “I” headwords
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Of or pertaining to a process that takes place at constant temperature
Corpus desk
Index EN-isothermal · isothermal · English
isothermal · rank #65,221 · 0 variants · 0 confusables
- FREQ-RARE #65,221
- LEN-MEGA 10 letters
- VOW-4 4 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-DENSE 17,902
- PHOTO-FINISH iwan
Nearest frequency peer: iwan (+1 rank slots)
Read with this headword: Spelling guide for this pattern
Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.
Frequency neighbourhood for “isothermal”
Lower corpus rank = more everyday usage (inverted bar length for readability)
- invigorate
invigorate
34,785 corpus weight
- inviolable
inviolable
34,784 corpus weight
- Ishaq
Ishaq
34,782 corpus weight
- isothermal
isothermal
34,780 corpus weight
- iwan
iwan
34,779 corpus weight
- kaleidoscop…
kaleidoscopic
34,775 corpus weight
What this shows Bars show where “isothermal” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.
| Property | Value |
|---|---|
| Headword | isothermal |
| Language | English |
| Part of speech | Adjective |
| Letters | 10 |
| Frequency rank | #65,221 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “isothermal” sits in English frequency
Rare enough to double-check
isothermal is uncommon English at frequency #65,221 among 17,902 “I” headwords, classed as anadjective. Rarity is why readers land here mid-draft. 2 senses are on record.
Our edit-distance generator produced no likely misspellings for isothermal, since its letter sequence doesn't invite the usual edit-distance slips. We don't track a confusable pairing for this entry, since nothing in our dataset looks or sounds close enough to cause mix-ups.
Etymologically, the entry records: From iso- + thermal or isotherm + -al. The correct English form is isothermal, spelled I-S-O-T-H-E-R-M-A-L.
Definition
- 1Of or pertaining to a process that takes place at constant temperature
- 2Of or pertaining to an isotherm
Etymology
From iso- + thermal or isotherm + -al.
This word in other languages
Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.
PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 6, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.
Frequently Asked Questions
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Similar English words by spelling shape
Same letter count and similar misspelling depth for "isothermal", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 10 letters (nearest by frequency rank).
Data Source
Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.