assertion

/əˈsɜːʃən/

//əˈsɜːʃən// noun

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

"assertion" is a 9-letter English headword indexed on PlainSpell.

The verdict

“assertion” is a moderately-common English word, ranked #12,366 in English word frequency and used as a noun.

#12,366
frequency rank, English
9
letters
12
tracked misspellings
2
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - The act of asserting; positive declaration or averment.

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

assertion vs assertive
78% similar
assertion vs asserting
78% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for assertion
PropertyValue
Headwordassertion
LanguageEnglish
Part of speechNoun
IPA/əˈsɜːʃən/
Letters9
Frequency rank#12,366
Misspellings tracked12
Confusable pairs2
SourceWiktionary (kaikki.org)

Where “assertion” 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). assertion lands here:

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

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

Spelling & Dictionary Insight

The English entry for assertion is 9 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /əˈsɜːʃən/. Corpus data places it at rank #12,366 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 6 distinct senses for this headword, so context determines which meaning a reader should apply.

Our generated misspelling index lists 12 likely wrong-spelling variants for assertion, with forms such as "asertion", "asesrtion", and "asseriton". Every one of these variants traces to a single-character edit -- an added or dropped letter, a swapped consonant, or a vowel swap -- the kind of slip a spell-checker is built to catch. It also participates in 2 confusable-pair relationships, "assertive", "asserting", a pairing that trips writers up because the two words share enough sound or shape to blur together.

Etymologically, the entry records: From Middle English assercioun, from Latin assertiō. By surface analysis, assert + -ion. The correct English form is assertion, spelled A-S-S-E-R-T-I-O-N.

Definition

  1. 1
    The act of asserting; positive declaration or averment.
  2. 2
    Something which is asserted; a declaration; a statement asserted.
  3. 3
    A statement or declaration which lacks support or evidence.
  4. 4
    Maintenance; vindication.
  5. 5
    A statement in a program asserting a condition expected to be true at a particular point, used in debugging.
  6. 6
    The set of information that the statement preparer is providing in a financial statement audit.

Etymology

From Middle English assercioun, from Latin assertiō. By surface analysis, assert + -ion.

Synonyms

accusationallegationcensurechargecriminationimpeachment

This word in other languages

afirmación(Español)assertion(Français)Versicherung(Deutsch)asserção(Português)

Common misspellings

Also misspelled as: asertion,asesrtion,asseriton,asserrtion,assersion,assertino,assertionn,assertoin,asserttion,assetrion,assretion,sasertion

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of assertion - measured in single-character edits (insert, delete, or substitute a letter). Larger bars are easier to catch; one-edit slips are the sneakiest.

asertion1asesrtion2asseriton2asserrtion1assersion1assertino2assertionn1assertoin2
Edit distance from "assertion"

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 "assertion"?
"assertion" is spelled A-S-S-E-R-T-I-O-N. The IPA pronunciation is /əˈsɜːʃən/.
What does "assertion" mean?
As a noun, "assertion" means: The act of asserting; positive declaration or averment.
What words are commonly confused with "assertion"?
"assertion" is commonly confused with "assertive", "asserting". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "assertion"?
The IPA (International Phonetic Alphabet) transcription for "assertion" is /əˈsɜːʃən/. 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 "assertion"?
From Middle English assercioun, from Latin assertiō. By surface analysis, assert + -ion. 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 “assertion”

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

  • The one correct English spelling is A-S-S-E-R-T-I-O-N - every other letter order is a misspelling in standard orthography.
  • Say it as /əˈsɜːʃən/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Don't mix it up with “assertive” - see the side-by-side comparison. assertion vs assertive
  • Browse more English words and confusable pairs in the same reference. English words
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