noun which may take the genitive case particle 'no'
Describes a person or thing that is completely unhelpful or fails to serve its purpose. Often used as a derogatory noun for a person.
He is a useless person who can't do anything.
This tool is broken and useless.
Compound of 役 (role, use) + 立たず, the negative continuative form of 立つ (to stand, to be useful). Literally 'not standing in a role', i.e., useless.