xiǔ​mù​bù​kě​diāo

hopeless case

朽木不可雕 xiǔ​mù​bù​kě​diāo
hopeless case
someone who is beyond reform, instruction, or improvement; often used to describe a person lacking character or potential
uncarvable wood
rotten wood that is too decayed or brittle to be carved into anything useful

Frequency

Written text
0.061 per million

Sources

Definitions
CC-CEDICT
Frequency data
BCC Corpus (BLCU)