'microgranite' originates from modern scientific English, specifically formed by combining the Greek prefix 'mikros' (via modern form 'micro-') meaning 'small' and the word 'granite' (from French 'granite', ultimately from Latin 'granum' meaning 'grain').

'microgranite' developed as a compound term in 19th-century geological literature (combining 'micro-' + 'granite') and was adopted into modern English geological vocabulary as 'microgranite'.

Initially it denoted simply 'a small-grained variety of granite'; this basic meaning has been retained, though usage has sometimes overlapped with related terms like 'aplite' or 'microgranular granite'.