'substructure' originates from Latin, specifically the word 'substructura,' where 'sub-' meant 'under' and 'structura' meant 'a building or structure.'

'substructura' transformed into the French word 'substructure,' and eventually became the modern English word 'substructure' through Middle English.

Initially, it meant 'an underlying structure,' and this meaning has largely remained the same in modern usage.