mental

Etymology 1

Borrowing from Middle French mental, from Late Latin mentālis, from mēns (“mind, disposition; heart, soul”) + -ālis (“-al”, adjectival suffix).

adj

1. (relational) Of or relating to the mind or specifically the total emotional and intellectual response of an individual to external reality.
   1. Of or relating to intellectual as contrasted with emotional activity.
      mental acuity
   2. Of, relating to, or being intellectual as contrasted with overt physical activity.
      Irregular bedtimes may disrupt healthy brain development in young children, according to a study of intelligence and sleeping habits. ¶ Going to bed at a different time each night affected girls more than boys, but both fared worse on mental tasks than children who had a set bedtime, researchers found. 2013-07-19, Ian Sample, “Irregular bedtimes may affect children's brains”, in The Guardian Weekly, volume 189, number 6, page 34
   3. Occurring or experienced in the mind.
   4. Relating to the mind, its activity, or its products as an object of study.
      mental science
   5. Relating to spirit or idea as opposed to matter.
      the distinction between physical things and mental ideas
2. Of, relating to, or affected by a psychiatric disorder.
   1. (relational) Intended for the care or treatment of persons affected by psychiatric disorders.
      mental hospitals
   2. (colloquial, UK, Ireland, Australia, New Zealand, dated in the US, comparable) Mentally disordered; insane, mad, crazy.
      He is the most mental freshman I've seen yet.
      He went mental on us.
3. (colloquial, UK, Ireland, Australia, New Zealand, comparable) Enjoyable or fun, especially in a frenetic way.
   That was a mental party last night.
4. Of or relating to telepathic or mind-reading powers.
   mental telepathy

Etymology 2

c. 1727, from Latin mentum (“the chin”) + -al.

adj

1. (anatomy, relational) Of or relating to the chin or median part of the lower jaw, genial.
   the mental nerve, the mental region
2. (biology, relational) Of or relating to the chinlike or liplike structure.

noun

1. (zootomy) A plate or scale covering the mentum or chin of a fish or reptile.