mental illness

noun

"mental-illness" is a 13-letter English headword indexed on PlainSpell.

The verdict

“mental illness” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
14
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The property of being mentally ill; mental disorders taken as a whole.

Corpus desk

Index EN-mental-illness · mental illness · English

mental illness · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-MEGA 14 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "M" thin
  • PHOTO-UNK Peer pending

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Key facts for mental illness
PropertyValue
Headwordmental illness
LanguageEnglish
Part of speechNoun
Letters14
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “mental illness” in English

mental illnessfalls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

mental illness is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. 2 senses are on record.

No generated misspelling entries exist for mental illness in our index, a sign its spelling follows regular English conventions. This headword has no recorded confusable partner, since nothing in our dataset looks or sounds close enough to cause mix-ups.

No explicit etymology string is stored for this entry, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is mental illness, spelled M-E-N-T-A-L- -I-L-L-N-E-S-S.

Definition

  1. 1
    The property of being mentally ill; mental disorders taken as a whole.
  2. 2
    A mental disorder.

Recorded use

Wiktionary examples

These source excerpts show how mental illness appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. Such studies show that geniuses are not any more likely to suffer from mental illness than the rest of us.
  2. Epilepsy is not a mental illness. It is caused by electrical changes in the brain.

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "mental illness"?
"mental illness" is spelled M-E-N-T-A-L- -I-L-L-N-E-S-S.
What does "mental illness" mean?
As a noun, "mental illness" means: The property of being mentally ill; mental disorders taken as a whole.
What language does "mental illness" come from?
"mental illness" is a English word. PlainSpell covers definitions, pronunciations, and spelling data across English, Spanish, Portuguese, French, and German.
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.

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

Source: FrequencyWords open word-frequency list