Late 19th century; earliest use found in English Historical Review. From Hellenistic Greek μυθοποιίαmythopoeia + -ism. Compare slightly earlier mythopoeic, mythopoesis.
Definition of mythopoeism in US English:
mythopoeism
nounˌmɪθə(ʊ)ˈpiːɪz(ə)m
Mythopoeia.
Origin
Late 19th century; earliest use found in English Historical Review. From Hellenistic Greek μυθοποιία mythopoeia + -ism. Compare slightly earlier mythopoeic, mythopoesis.