"of or pertaining to temperament," 1640s, from temperament + -al (1); in the sense of "moody" it is recorded from 1907. Related: Temperamentally.
Entries linking to temperamental
temperament n.
late 14c., "proportioned mixture of elements," from Latin temperamentum "proper mixture, a mixing in due proportion," from temperare "to mix in due proportion, modify, blend; restrain oneself" (see temper (v.)). In old medicine, it meant a combination of qualities (hot, cold, moist, dry) that determined the nature of an organism; thus also "a combination of the four humors (sanguine, choleric, phlegmatic, and melancholic) that made up a person's characteristic disposition." General sense of "habit of mind, natural disposition" is from 1821.
-al 1
suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).