isotonic

Name: isotonic, English Word Data
Creator: Wiktionary
License: https://creativecommons.org/licenses/by-sa/4.0/

/ˌɑɪ.səˈtɑː.nɪk/

//ˌɑɪ.səˈtɑː.nɪk// adj

By PlainSpell · According to Wiktionary data (CC BY-SA) · analyzed May 6, 2026

The verdict

“isotonic” is uncommon English (frequency #92,738 among 17,902 “I” headwords), classed as an adjective. The kind of spelling people second-guess.

#92,738
frequency rank, English: 17,902
“I” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Having the same osmotic pressure.

Key facts for isotonic
Property	Value
Headword	isotonic
Language	English
Part of speech	Adjective
IPA	/ˌɑɪ.səˈtɑː.nɪk/
Letters	8
Frequency rank	#92,738
Misspellings tracked	0
Confusable pairs	0
Source	Wiktionary (kaikki.org)

Where “isotonic” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right). isotonic lands here:

#92,738

#1#100#1K#10K#100K

← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Rare enough to double-check

isotonic is uncommon English at frequency #92,738 among 17,902 “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
Having the same osmotic pressure.
2
Having the same concentration of solutes as human blood.
3
Having equal tension.
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
Having the same tone.

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.

Using “isotonic”

The practical upshot for anyone who landed here from a spell-check.

The one correct English spelling is I-S-O-T-O-N-I-C - every other letter order is a misspelling in standard orthography.
Say it as /ˌɑɪ.səˈtɑː.nɪk/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
Browse more English words and confusable pairs in the same reference. English words

Other uncommon English words near this 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.