Latin 'mens' (mind), from PIE *men- (to think) — produced 'mental,' 'mention,' 'comment,' 'dementia,' and 'monument.'
A Latin word meaning 'mind, intellect, reason, judgment, intention,' and the source of numerous English words relating to mental activity, memory, and thought.
From Proto-Italic *mentis, from the Proto-Indo-European root *men- meaning 'to think.' Latin mēns (stem ment-) covered the full range of mental activity: the mind as a faculty, the intellect, understanding, thought, intention, disposition, and courage. The PIE root *men- is one of the most important roots for the vocabulary of cognition across Indo-European languages, producing Sanskrit manas ('mind'), Greek μένος (ménos, 'spirit, force') and related forms, and the Germanic source of English 'mind' itself. Key
The English word 'mind' and the Latin word 'mēns' are cousins from the same PIE root *men- ('to think'), but they arrived in English by completely different routes — 'mind' through Proto-Germanic *gamundiz (memory, thought), and 'mental' directly from Latin mentālis. The Latin phrase 'mēns rea' ('guilty mind') remains a cornerstone of criminal law in English-speaking countries: you cannot be convicted of a crime without proof that your mind intended it.