below standard or less than adequate

substandard housing conditions.

noting or pertaining to a dialect or variety of a language or a feature of usage that is often considered by others to mark its user as uneducated; nonstandard.

Insurance .

not measuring up to an insurer's regular standards in undertaking risks

a substandard risk.

pertaining to insurance written to cover substandard risks.

adjective

bad , base , below average , below par , below standard , cheap , inadequate , junk * , lemon * , lousy , low-grade , poor , second-rate , shoddy , subpar , unacceptable , common , low-quality , mean , mediocre , second-class , shabby