Burnt-up is an idiomatic expression that describes a situation or a person who is exhausted, overwhelmed, or irritable. When looking for synonyms, one might consider words that suggest a similar sense of fatigue or depletion. Some possibilities might include: worn-out, fatigued, strained, depleted, spent, drained, tired, frazzled, shattered, or exhausted. Each of these words connotes a sense of physical or emotional weariness, suggesting someone or something that has been pushed beyond its limits. Whether describing a person, a situation, or an object, these synonyms can help readers understand the extent of the depletion or exhaustion being discussed.