Compos mentis

Compos mentis is an adjective that means having full control of one’s mind. Our word of the day comes directly from a Latin phrase that translates to ‘having the mastery of one’s mind.’ It is frequently used in a legal context. When Carl wrote his will, he began with the usual declaration of being compos mentis. But that strange shirt he was wearing would suggest he may have been sane, but he was a little weird.