taru-adjective, adverb taking the 'to' particle
assiduously; with unremitting zeal
Rare literary four-character compound describing diligent, tireless effort. Often used in formal or written contexts.
彼は孜々営々と研究に励んだ。
He devoted himself assiduously to his research.
Common onomatopoeic adverb for steady, diligent work. Much more everyday than 孜々営々.
Part of the compound; alone it also means 'assiduously' but is less common and often used in 営々と.
A yojijukugo (four-character compound) combining 孜々 (diligent) and 営々 (tireless effort). The exact historical derivation is uncertain; the spelling is conventionally associated with these meanings.