'idyllism' originates from Modern English, specifically formed from the noun 'idyll' with the suffix '-ism'. The noun 'idyll' itself comes from Greek 'eidyllion', where 'eidos' meant 'form, shape' and the diminutive element '-yllion' implied a 'little picture' or 'small scene'.

'idyllism' developed after the noun 'idyll' entered English via Latin and French forms; Greek 'eidyllion' passed into Medieval Latin and later Middle English as 'idyll', and the modern English formation 'idyllism' arose by adding the suffix '-ism' to express a quality, doctrine, or tendency.

Initially, related words referred to a 'little picture' or a short pastoral poem/scene; over time the sense broadened to denote 'pastoral or idealized scenes' and eventually the abstract quality or advocacy of such idealized life, now expressed as 'idyllism'.