'idyllicism' originates from Greek, specifically the word 'eidyllion', where 'eidyllion' (diminutive of 'eidos') meant 'little form' or 'little picture'; the element '-ism' is a suffix from Greek/Latin used to form nouns denoting doctrines or practices.

'idyllicism' developed from the adjective 'idyllic' (from English 'idyll' < Middle English/French < Latin < Greek 'eidyllion') combined with the suffix '-ism' (from Greek/Latin), producing the noun meaning 'the practice or tendency of being idyllic'.

Initially, related words like 'idyll' referred specifically to a short poem or piece depicting pastoral life; over time the sense broadened so that 'idyllicism' denotes a general quality, tendency, or doctrine of idealizing simple/pastoral life.