khiak-khóo刻苦

industrious

industrious; assiduous; diligent; basic; frugal; industriously; assiduously; diligently; hard; to treat harshly

adverb

English Wiktionary, “刻苦” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E5%88%BB%E8%8B%A6 · confidence: Medium (Wiktionary, Hokkien)