addendum
/əˈdɛn.dəm/
"addendum" is a 8-letter English headword indexed on PlainSpell.
The verdict
“addendum” is a moderately-common English word, ranked #33,106 in English word frequency and used as a noun.
- #33,106
- frequency rank, English
- 8
- letters
- 10
- tracked misspellings
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Something to be added; especially text added as an appendix or supplement to a document.
| Property | Value |
|---|---|
| Headword | addendum |
| Language | English |
| Part of speech | Noun |
| IPA | /əˈdɛn.dəm/ |
| Letters | 8 |
| Frequency rank | #33,106 |
| Misspellings tracked | 10 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “addendum” sits in English frequency
Spelling & Dictionary Insight
The English entry for addendum is 8 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /əˈdɛn.dəm/. Corpus data places it at rank #33,106 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 3 distinct senses for this headword, so context determines which meaning a reader should apply.
Our generated misspelling index lists 10 likely wrong-spelling variants for addendum, with forms such as "addednum", "addenddum", and "addendmu". Each of these forms differs from the correct spelling by one small edit: a doubled letter, a dropped silent letter, or a substituted vowel. This entry stands alone in our confusable dataset, a sign it's visually distinctive enough not to be mixed up with another word.
Etymologically, the entry records: From the gerundive of Latin addere (“to add”). The correct English form is addendum, spelled A-D-D-E-N-D-U-M.
Definition
- 1Something to be added; especially text added as an appendix or supplement to a document.
- 2A postscript.
- 3The height by which the tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line.
Etymology
From the gerundive of Latin addere (“to add”).
This word in other languages
Common misspellings
Also misspelled as: addednum,addenddum,addendmu,addendumm,addenndum,addenudm,addnedum,adedndum,adendum,dadendum
Misspelling Pattern Breakdown
How far each generated variant is from the correct spelling of addendum - counted as single-character edits (an insertion, a deletion, or a substituted letter). The larger the bar, the easier the typo is to spot; one-edit slips are the ones that sneak past readers.
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 "addendum"?
What does "addendum" mean?
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Using “addendum”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is A-D-D-E-N-D-U-M - every other letter order is a misspelling in standard orthography.
- Say it as /əˈdɛn.dəm/ (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
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.