mentally ill

adj

"mentally-ill" is a 11-letter English headword indexed on PlainSpell.

The verdict

“mentally ill” is uncommon English (outside the top frequency list), classed as an adjective. The kind of spelling people second-guess.

Unranked
below top-frequency English
12
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Having a psychological disorder.

Corpus desk

Index EN-mentally-ill · mentally ill · English

mentally ill · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-MEGA 12 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 mentally ill
PropertyValue
Headwordmentally ill
LanguageEnglish
Part of speechAdjective
Letters12
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “mentally ill” in English

mentally illfalls 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

mentally ill is uncommon English outside the top frequency list, classed as anadjective. Rarity is why readers land here mid-draft. Gloss: "Having a psychological disorder.".

No misspelling variants are generated for mentally ill in our index, suggesting the orthography follows predictable English patterns. This entry stands alone in our confusable dataset, since its spelling is unusual enough that it doesn't cluster with a lookalike.

This entry carries no recorded etymology, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is mentally ill, spelled M-E-N-T-A-L-L-Y- -I-L-L.

Definition

  1. 1
    Having a psychological disorder.

Recorded use

Wiktionary example

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

  1. The mentally ill are to be part of the assisted dying debate.

Synonyms

crazyinsanenot all there

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 "mentally ill"?
"mentally ill" is spelled M-E-N-T-A-L-L-Y- -I-L-L.
What does "mentally ill" mean?
As an adjective, "mentally ill" means: Having a psychological disorder.
What language does "mentally ill" come from?
"mentally ill" is a English word. PlainSpell's reference spans five languages -- English, Spanish, Portuguese, French, and German -- with definitions, pronunciations, and spelling data for each.
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