'irregularly-spaced' originates from the combination of 'irregularly' and 'spaced', where 'irregularly' is derived from 'irregular', meaning 'not regular', and 'spaced' from 'space', meaning 'to arrange with intervals'.

'Irregularly' evolved from the Latin word 'irregularis', and 'spaced' from the Old French 'espacier', eventually forming the modern English term 'irregularly-spaced'.

Initially, 'irregularly' meant 'not conforming to a rule', and 'spaced' meant 'arranged with intervals'. Together, they describe something not evenly arranged.