sub-standard

/S AH1 B S T AE0 N D ER0 D/
adjective
  1. 1

    Of inferior quality; not meeting the minimum quality requirements.

    โ€œThey built this with substandard parts. No wonder it collapsed.โ€

  2. 2

    Not conforming to the standard variety; nonstandard.

Source: https://en.wiktionary.org/wiki/sub-standard, https://en.wiktionary.org/wiki/substandard