mononucleosis

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

/ˌmɑnoʊnukliˈoʊsɪs/

//ˌmɑnoʊnukliˈoʊsɪs// noun

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

The verdict

“mononucleosis” is uncommon English (frequency #92,891 among 36,575 “M” headwords), classed as a noun. The kind of spelling people second-guess.

#92,891
frequency rank, English: 36,575
“M” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A viral infection marked by extreme fatigue, high fever, and swollen lymph nodes.

Key facts for mononucleosis
Property	Value
Headword	mononucleosis
Language	English
Part of speech	Noun
IPA	/ˌmɑnoʊnukliˈoʊsɪs/
Letters	13
Frequency rank	#92,891
Misspellings tracked	0
Confusable pairs	0
Source	Wiktionary (kaikki.org)

Where “mononucleosis” 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). mononucleosis lands here:

#92,891

#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

mononucleosis is uncommon English at frequency #92,891 among 36,575 “M” headwords, classed as anoun, transcribed /ˌmɑnoʊnukliˈoʊsɪs/. Rarity is why readers land here mid-draft. Gloss: "A viral infection marked by extreme fatigue, high fever, and swollen lymph nodes.".

mononucleosis has no tracked misspelling variants, since its letter pattern doesn't lend itself to common typo substitutions. This headword has no recorded confusable partner, since its spelling is unusual enough that it doesn't cluster with a lookalike.

Etymologically, the entry records: From mono- + nucleus + -osis. The correct English form is mononucleosis, spelled M-O-N-O-N-U-C-L-E-O-S-I-S.

Definition

1
A viral infection marked by extreme fatigue, high fever, and swollen lymph nodes.

Etymology

From mono- + nucleus + -osis.

This word in other languages

mononucleosis(Español)mononucléose(Français)Pfeiffer-Drüsenfieber(Deutsch)

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 "mononucleosis"?

"mononucleosis" is spelled M-O-N-O-N-U-C-L-E-O-S-I-S. The IPA pronunciation is /ˌmɑnoʊnukliˈoʊsɪs/.

What does "mononucleosis" mean?

As a noun, "mononucleosis" means: A viral infection marked by extreme fatigue, high fever, and swollen lymph nodes.

How do you pronounce "mononucleosis"?

The IPA (International Phonetic Alphabet) transcription for "mononucleosis" is /ˌmɑnoʊnukliˈoʊsɪs/. 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 "mononucleosis"?

From mono- + nucleus + -osis. 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 “mononucleosis”

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

The one correct English spelling is M-O-N-O-N-U-C-L-E-O-S-I-S - every other letter order is a misspelling in standard orthography.
Say it as /ˌmɑnoʊnukliˈoʊsɪs/ (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.