This is the 4331st most frequent German word.
fleißig
Hardworking.
Used as an adjective to describe someone who is hardworking.
Er ist ein fleißiger Arbeiter.
He is a diligent worker.
Used as an adverb to describe the manner in which someone works.
Sie arbeitet fleißig an ihrem Projekt.
She is working diligently on her project.
Used in a nominalized form to express the concept of diligence generally.