noun-modifying (irregular), na-adjective, noun which may take the genitive case particle 'no', noun
worn-out; run-down; shabby; dilapidated
Describes something old, broken-down, or in poor condition, often with a nuance of being barely functional. Can be used for objects, buildings, vehicles, etc.
He commutes to school on a worn-out bicycle.
This apartment is run-down, but the rent is cheap.
The word is likely derived from the prefix おん- (emphatic) and ぼろ (rag, tatters), but the exact derivation is uncertain.