'substandard' originates from the prefix 'sub-' meaning 'below' and the word 'standard', which comes from Old French 'estandart', meaning 'a rallying place'.

'substandard' was formed in English by combining 'sub-' with 'standard', reflecting the idea of being below the accepted level.

Initially, it meant 'below the accepted level', and this meaning has largely remained the same in modern usage.