'nonhierarchical' originates from Modern English, specifically the prefix 'non-' (from Latin 'non', meaning 'not') combined with 'hierarchical' (from French 'hiérarchique', ultimately from Greek 'hierarkhia'), where 'non-' meant 'not' and the elements of 'hierarkhia' related to 'sacred' and 'rule'.

'hierarkhia' (Greek) changed into Old French/Medieval Latin forms and then into English as 'hierarchy' and the adjective 'hierarchical'; the modern compound 'nonhierarchical' developed in Modern English by adding the productive negative prefix 'non-' to 'hierarchical'.

Initially 'hierarkhia' referred to 'rule (or order) of priests/sacred rulers' and later generalized to mean a system of ranked order; over time 'hierarchical' came to mean 'arranged in levels or ranks', and 'nonhierarchical' evolved to mean 'not arranged in ranks' or 'lacking a hierarchy'.