'antidemocratical' originates from the prefix 'anti-' (from Greek 'anti' meaning 'against') combined with 'democratic', which ultimately comes from Greek 'dēmokratia' (specifically the elements 'dēmos' meaning 'people' and 'kratos' meaning 'power' or 'rule').

'antidemocratical' developed in English by attaching the prefix 'anti-' to 'democratic' (itself borrowed via Latin/French from Greek 'dēmokratia'); the adjectival suffix '-ical' reflects later English formation parallel to '-ic' variants (hence the coexistence of 'antidemocratic' and 'antidemocratical').

Initially it meant 'against democracy' and over time has retained that core sense, though the '-ical' form has become relatively rare or marked compared with 'antidemocratic'.