mental (adj.)

early 15c., "in, of, or pertaining to the mind; characteristic of the intellect," from Late Latin mentalis "of the mind," from Latin mens (genitive mentis) "mind," from PIE root *men- (1) "to think."

In Middle English, also "of the soul, spiritual." From 1520s as "done or performed in the mind." Meaning "crazy, deranged" is by 1927, probably from combinations such as mental patient (1859); mental hospital (1891). Mental health is attested by 1803; mental illness by 1819; mental retardation by 1904.

Definitions of mental

mental (adj.)
involving the mind or an intellectual process;
mental suffering
mental calculations
in a terrible mental state
mental images of happy times
free from mental defects
mental (adj.)
of or relating to the mind;
mental development
mental powers
mental hygiene
mental (adj.)
of or relating to the chin- or liplike structure in insects and certain mollusks;
mental (adj.)
of or relating to the chin or median part of the lower jaw;
Synonyms: genial
mental (adj.)
affected by a disorder of the mind;
a mental patient
mental illness