Crossword Dictionary

temperamental

erratic, temperamental - a 
likely to perform unpredictably; "erratic winds are the bane of a sailor"; "a temperamental motor; sometimes it would start and sometimes it wouldn't"; "that beautiful but temperamental instrument the flute"- Osbert Lancaster 

wordplays

synonyms

capricious, changeable, changeful, fickle, fluctuating, fluid, freakish, impulsive, inconstant, mercurial, mutable, uncertain, unsettled, unstable, unsteady, variable, volatile, whimsical

in a sentence

The actor is known for being temperamental.  

The old computer is temperamental.  

They divorced due to temperamental differences.

merriam-webster

etymology

[temperment] 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.

etymonline