IPA: //sʌbˈstændərd//
KK: /sʌbˈstændərd/
Not meeting the required quality or standard; inferior in quality.
The substandard materials used in the construction led to many problems.
Comparative: more substandard
Superlative: most substandard
Substandard → It is formed from "sub-" (meaning under or below) and "standard" (from Old French *estandard*, meaning a level of quality or measure). The word "substandard" means below the accepted level of quality or measure.
Think of something that is 'under' ('sub-') the expected 'level of quality' ('standard') — that's why substandard refers to something that does not meet the required standards.