the.com/temperament

means A person's characteristic pattern of mood, reactivity, and energy — the underlying disposition that shapes how they respond to the world.

from From Latin 'temperamentum,' meaning a proper mixing or balancing of elements — rooted in 'temperare,' to mix in due proportion (the same root gives us 'temper' and 'temperature'). The word carries the ghost of ancient humoral medicine, where personality was thought to result from the balance of four bodily fluids — blood, phlegm, black bile, yellow bile — and a well-'tempered' person was one whose mix was in harmony. The psychology is long outdated, but the metaphor of inner balance stuck.