'petrology' originates from Greek, specifically the words 'petra' and 'logos', where 'petra' meant 'rock' and 'logos' meant 'study' or 'discourse'.

'petrology' changed from New Latin 'petrologia' and eventually became the modern English word 'petrology'.

Initially, it meant 'the study of rocks', and over time this core meaning has been retained while usage has narrowed to the scientific discipline within geology.