Main Page | See live article | Alphabetical index The term non compos mentis comes from Latin, non meaning "not," compos meaning "in control," and mentis, genitive singular of mens, mind. and means not having a sound mind; not sane. (See also compos mentis, the antonym.) This is rarely used in its opposite form, compos mentis, that is, having control of one's faculties. Usually one hears a phrase such as "It was determined that the criminal was non compos mentis" (i.e., insane, not fit to stand trial); one might sometimes say the criminal was compos mentis, i.e., the criminal had full knowledge of his/her actions and is competent to stand trial. It is typically a legal term, but (in the slang of the United States at least) one often hears phrases such as, "That friend of yours was non compos mentis after getting fired." This article is a stub. You can help Wikipedia by fixing it. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.