Why is the ninth month called September?
early 15c., "pertaining to the mind," from Middle French mental, from Late Latin mentalis "of the mind," from Latin mens (genitive mentis) "mind," from PIE root *men- "to think" (cf. Sanskrit matih "thought, mind," Gothic gamunds, Old English gemynd "memory, remembrance;" see mind (n.)). Meaning "crazy, deranged" is from 1927, probably from combinations such as mental hospital.
mental men·tal1 (měn'tl)
Of or relating to the mind; intellectual.
Of, relating to, or affected by a disorder of the mind.
Intended for treatment of people affected with disorders of the mind.
Of or relating to the chin.