ἀχρεῖος/achreios

This word describes someone. It is an adjective.

This word can mean useless or worthless. When this word is used in this way, it describes someone who is given a duty but performs it poorly.
This word can mean unworthy. When this word is used in this way, it describes someone who does not deserve praise or reward for their efforts.

See: Matthew 25:30; Luke 17:10