non compos mentis

American  

[nohn kohm-pohs men-tis, non kom-puhs men-tis] / ˈnoʊn ˈkoʊm poʊs ˈmɛn tɪs, ˈnɒn ˈkɒm pəs ˈmɛn tɪs /

adjective

Latin.

1. not of sound mind; mentally incapable of managing one's affairs (used especially in a legal context).

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non compos mentis British  

/ ˈnɒn ˈkɒmpəs ˈmɛntɪs /

adjective

1. mentally incapable of managing one's own affairs; of unsound mind

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non compos mentis Cultural  

1. A phrase used to describe someone who is out of his or her mind and therefore not legally responsible for his or her actions: “It was determined by the court that the killer was non compos mentis.” From Latin, meaning “not having control of the mind.”

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Etymology

Origin of non compos mentis

Latin: not in control of one's mind

Example Sentences

When you watch it, you can see quite clearly, with the benefit of hindsight, that he is non compos mentis.

From The Guardian • Sep. 8, 2010

In London, a coroner found that the late Sidney Corrall, acquisitive but non compos mentis, had swallowed and kept all to himself 201 pennies, florins, shillings, halfpennies, sixpences, half crowns, and threepenny bits.

From Time Magazine Archive

If anyone proposes another match race between these two super horses,” wrote a reporter after the race, “henceforth, he will be tried in the morning for treason, mutiny, mopery and non compos mentis.'''’

From "Seabiscuit: An American Legend" by Laura Hillenbrand

From such a condition the law clearly distinguished the lunatic, or non compos mentis, who is "one who hath had understanding, but by disease, grief, or other accident hath lost the use of his reason."

From Chapters in the History of the Insane in the British Isles by Tuke, Daniel Hack

The ships became, as you might say, non compos mentis.

From A Spaceship Named McGuire by Garrett, Randall