From Latin 'mens' (mind), from PIE *men- (to think) — same root as 'mind,' 'memory,' 'mentor,' and 'mania.'
Relating to the mind; carried out by or taking place in the mind.
From Late Latin mentalis (of the mind), from Latin mens, mentis (mind, intellect, reason, intention), from PIE *men- (to think). This root is extraordinarily productive: it yields Sanskrit manas (mind), Greek menos (spirit, force) and mania (madness), Lithuanian mintis (thought), and English mind itself via Germanic *mundaz. The Latin mens distinguished rational thought from animus (the animating spirit) and
In British English slang, 'mental' has come to mean 'crazy' or 'wildly exciting' — a usage that directly echoes the Latin root. Latin 'dēmēns' (out of one's mind, mad) is simply 'dē-' (away from) + 'mēns' (mind), and 'demented' still carries that formal meaning. The slang use of 'mental' has simply compressed the same idea: being so far outside the normal workings