taru-adjective, adverb taking the 'to' particle
quietly and assiduously
Describes working steadily and silently, often with dedication. A literary, somewhat formal expression; used adverbially with と or as a たる adjective.
He continued his research quietly and assiduously.
Their quiet, assiduous efforts bore fruit.
Standard kanji form using 々 for repetition.
Full kanji form without repetition marks; less common but still seen.
Compound of 営々 (diligently, from reduplication of 営 'work') and 黙々 (silently, from reduplication of 黙 'silent'). The exact historical derivation is uncertain, but the combination is a natural pairing of two reduplicated kanji compounds.