adjective
mentally ill
MEN-tuh-lee IL
Mentally ill (adjective) means suffering from a diagnosable psychiatric condition that significantly affects thinking, mood or behaviour. Example: “He was seriously mentally ill and had been off his medication for weeks.”
adjective
1
Suffering from a diagnosable psychiatric condition that significantly affects thinking, mood or behaviour.
"He was seriously mentally ill and had been off his medication for weeks."
"The report found many mentally ill prisoners receive no treatment at all."
2
informal, often considered offensive Used loosely and jokingly of behaviour or things thought to be wildly excessive or irrational.
"Paying four hundred quid for a hoodie is mentally ill behaviour."
How to use mentally ill
Learner’s notesIn plain EnglishHaving a psychiatric condition that affects how you think, feel or behave.
When to use it
Acceptable in clinical and journalistic use; person-first phrasing is preferred in careful writing, and the slang use is best avoided.
Easily confused with
Common pairings
severely mentally ill
the mentally ill
mentally ill patients
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He was seriously _____ and had been off his medication for weeks.
Synonyms
View more →Antonyms
mentally healthy
of sound mind
Related words
Frequently asked questions
What is the difference between mentally ill and mentally disabled?
Mental illness is a condition affecting mood, thinking or perception, such as depression or schizophrenia, and it often fluctuates or can be treated. Mental or intellectual disability refers to lifelong limits on intellectual functioning, such as Down's syndrome, and is not an illness.
Is 'mentally ill' offensive?
The term itself is clinical and accurate, but many clinicians and advocacy groups prefer person-first wording such as 'a person with a mental illness' rather than labelling someone as their condition. Using it as an insult for ordinary behaviour is widely considered offensive.
What is the meaning of mentally ill?
"mentally ill" (adjective) means suffering from a diagnosable psychiatric condition that significantly affects thinking, mood or behaviour.
What is another word for mentally ill?
Other words for "mentally ill" include mentally unwell, psychiatrically ill, unhinged, deranged.
