burned-out

The compound adjective "burned-out" is a metaphorical extension of a literal firefighting and industrial term. Literally, it describes a building or object that has been completely consumed by fire, leaving only ashes and a hollow shell. The participle form "burned" (or "burnt") combined with the intensifying particle "out" conveys a sense of total consumption. By the mid-20th century, this vivid imagery was applied to human psychology and physiology, first in clinical contexts to describe extreme fatigue from chronic stress, and later more broadly to describe anyone depleted of energy, motivation, or effectiveness, as if their inner resources had been entirely burned up.

Structure: burn (to be on fire) + ed (past participle suffix) + out (completely) - burn: From Old English beornan (intransitive) and bærnan (transitive), meaning "to be on fire, to consume by fire." Germanic origin. - ed: A suffix forming the past tense and past participle of regular verbs, from Old English -ede, -ode, -ade. - out: From Old English ūt, meaning "outward, outside, away." Germanic origin, used here as an adverbial particle to indicate completeness or exhaustion.