isotonic

/ˌɑɪ.səˈtɑː.nɪk/

//ˌɑɪ.səˈtɑː.nɪk// adj

By · According to Wiktionary data (CC BY-SA) ·

"isotonic" is a 8-letter English headword indexed on PlainSpell.

The verdict

“isotonic” is uncommon English (frequency #92,738 among 2,140 “I” headwords), classed as an adjective. The kind of spelling people second-guess.

#92,738
frequency rank, English
2,140
“I” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Having the same osmotic pressure.

Corpus desk

Index EN-isotonic · isotonic · English

isotonic · rank #92,738 · 0 variants · 0 confusables

  • FREQ-RARE #92,738
  • LEN-LONG 8 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 2,140
  • PHOTO-FINISH Itzhak

Nearest frequency peer: Itzhak (+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.

Long-tail ranks near “isotonic”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “isotonic” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for isotonic
PropertyValue
Headwordisotonic
LanguageEnglish
Part of speechAdjective
IPA/ˌɑɪ.səˈtɑː.nɪk/
Letters8
Frequency rank#92,738
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “isotonic” in English

Word frequency stretches from the small set of words we reach for constantly (left) out to the long tail barely used once in a while (right).isotonicfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Rare peers in the same band: “Itzhak” (#92,739), “ipsilateral” (#92,736), “iPSC” (#92,735). Among 2,140 “I” headwords, “isotonic” is #92,738. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

isotonic is uncommon English at frequency #92,738 among 2,140 “I” headwords, classed as anadjective, transcribed /ˌɑɪ.səˈtɑː.nɪk/. Rarity is why readers land here mid-draft. 5 senses are on record.

We couldn't generate a plausible misspelling set for isotonic, suggesting the orthography follows predictable English patterns. No confusable counterpart is on file for this word, since its spelling is unusual enough that it doesn't cluster with a lookalike.

Etymologically, the entry records: From iso- + tonic. The correct English form is isotonic, spelled I-S-O-T-O-N-I-C.

Definition

  1. 1
    Having the same osmotic pressure.
  2. 2
    Having the same concentration of solutes as human blood.
  3. 3
    Having equal tension.
  4. 4
    Of or involving muscular contraction against resistance in which the length of the muscle changes. Antonym is isometric. Isotonic movements are either concentric (working muscle shortens) or eccentric (working muscle lengthens). See also Wikipedia:Isotonic (exercise physiology)
  5. 5
    Having the same tone.

Recorded use

Wiktionary example

These source excerpts show how isotonic appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. Use an isotonic saline solution in your neti pot to prevent irritation of your nasal passages.

Etymology

From iso- + tonic.

This word in other languages

isotonique(Français)isotonisch(Deutsch)isotónico(Português)

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.

Frequently Asked Questions

How do you spell "isotonic"?
"isotonic" is spelled I-S-O-T-O-N-I-C. The IPA pronunciation is /ˌɑɪ.səˈtɑː.nɪk/.
What does "isotonic" mean?
As an adjective, "isotonic" means: Having the same osmotic pressure.
How do you pronounce "isotonic"?
The IPA (International Phonetic Alphabet) transcription for "isotonic" is /ˌɑɪ.səˈtɑː.nɪk/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "isotonic"?
From iso- + tonic. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "isotonic", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 8 letters (nearest by frequency rank).

inoculum#92,727jokester#92,750Kattegat#92,759Hollings#92,694

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list