exothermic

adj

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

"exothermic" is a 10-letter English headword indexed on PlainSpell.

The verdict

“exothermic” is uncommon English (frequency #69,836 among 18,836 “E” headwords), classed as an adjective. The kind of spelling people second-guess.

#69,836
frequency rank, English
18,836
“E” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - That releases energy in the form of heat.

Key facts for exothermic
PropertyValue
Headwordexothermic
LanguageEnglish
Part of speechAdjective
Letters10
Frequency rank#69,836
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “exothermic” 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). exothermic lands here:

#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

exothermic is uncommon English at frequency #69,836 among 18,836 “E” headwords, classed as anadjective. Rarity is why readers land here mid-draft. 3 senses are on record.

The misspelling generator found no plausible variants for exothermic, a sign its spelling follows regular English conventions. No confusable counterpart is on file for this word, which typically means the spelling is too distinctive to be mistaken for another word.

Etymologically, the entry records: From French exothermique, from exo- (“outside”) + thermique (“of heat”), both ultimately from Ancient Greek. By surface analysis, exo- + -thermic. The correct English form is exothermic, spelled E-X-O-T-H-E-R-M-I-C.

Definition

  1. 1
    That releases energy in the form of heat.
  2. 2
    That releases heat during its formation, and absorbs it during its decomposition.
  3. 3
    Of an animal: whose body temperature is regulated by external factors; cold-blooded.

Etymology

From French exothermique, from exo- (“outside”) + thermique (“of heat”), both ultimately from Ancient Greek. By surface analysis, exo- + -thermic.

Synonyms

exothermal

Antonyms

endothermic

This word in other languages

exotherm(Deutsch)exotérmico(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 "exothermic"?
"exothermic" is spelled E-X-O-T-H-E-R-M-I-C.
What does "exothermic" mean?
As an adjective, "exothermic" means: That releases energy in the form of heat.
What is the origin of the word "exothermic"?
From French exothermique, from exo- (“outside”) + thermique (“of heat”), both ultimately from Ancient Greek. By surface analysis, exo- + -thermic. 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 “exothermic”

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

  • The one correct English spelling is E-X-O-T-H-E-R-M-I-C - every other letter order is a misspelling in standard orthography.
  • 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.

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

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list