taru-adjective, adverb taking the 'to' particle
tired out; exhausted; weary
Rare literary word, typically used in classical or highly formal writing. Describes a state of being thoroughly fatigued, often with a poetic or emphatic tone. Functions as a taru-adjective or adverb with と.
彼は労々として家路についた。
He headed home, utterly exhausted.
労々たる様子で、彼女は椅子に腰を下ろした。
Looking completely worn out, she sat down on the chair.
Colloquial onomatopoeic word for being exhausted; 労々 is formal and archaic.
Reduplication of 労 (ろう, 'labor, toil'), emphasizing the state of being worn out from effort. The exact historical derivation is uncertain, but it follows a classical pattern of forming adjectives through repetition.