mental (adj.) Look up mental at Dictionary.com
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" (cognates: 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.