'subterrestrial' originates from Latin, specifically the elements 'subter' and 'terra', where 'subter' meant 'under' and 'terra' meant 'earth'.

'subterrestrial' was formed in English by combining the Latin element 'subter' with 'terrestrial' (from Latin 'terra' + the adjectival suffix '-alis'); the word entered English as a learned formation paralleling 'terrestrial' with the prefix 'sub-'.

Initially it conveyed the basic sense 'under the earth', and over time it has come to be used to mean specifically 'beneath the earth's surface; subterranean' in descriptive and scientific contexts.