Late 18th century; earliest use found in Fanny Burney (1752–1840), writer. Irregularly from the name of Morpheus + -ic, after adjectives ending in -etic.
Definition of morphetic in US English:
morphetic
adjectivemɔːˈfɛtɪk
rare
Of or relating to sleep or dreams.
Origin
Late 18th century; earliest use found in Fanny Burney (1752–1840), writer. Irregularly from the name of Morpheus + -ic, after adjectives ending in -etic.