'irregularly-divided' originates from the combination of 'irregularly' and 'divided', where 'irregularly' comes from Latin 'irregularis', meaning 'not regular', and 'divided' from Latin 'dividere', meaning 'to separate'.

'Irregularis' transformed into the Old French 'irregulier', and eventually became the modern English word 'irregular'. 'Dividere' transformed into the Old French 'diviser', and eventually became the modern English word 'divide'.

Initially, 'irregularly' meant 'not following a pattern', and 'divided' meant 'separated into parts'. The combined term 'irregularly-divided' retains these meanings in modern usage.