'subgroup' originates from the prefix 'sub-' meaning 'under' or 'below' and the word 'group', which comes from the Old French 'groupe', meaning 'cluster' or 'knot'.

'subgroup' evolved from the combination of 'sub-' and 'group', which was used in Middle English as 'groupe'.

Initially, it meant 'a group within a group', and this meaning has largely remained the same in modern usage.