adjective
hardworking, diligent
A2
'fleißig' means hardworking or diligent. It's a gradable adjective: comparative fleißiger, superlative am fleißigsten. Common antonyms: faul and müßig. Not a participle. Use like any adjective with standard endings (e.g., ein fleißiger Schüler). It can be used attributively or predicatively and can modify people.
Examples
Die Firma beförderte Maria, weil sie sehr fleißig arbeitete.
The company promoted Maria because she worked very hard.
Sie ist sehr fleißig und lernt jeden Tag.
She is very hardworking and studies every day.
Ein fleißiger Schüler macht seine Hausaufgaben.
A diligent student does his homework.
Details
Mnemonics
Imagine someone studying late with many books and a lamp — that person is fleißig.
Think 'flies' working — 'fleißig' = busy as flies (visual pun).
visual anchor rather than gender (adjective).
Notes
A positive character trait commonly used to describe students or employees.