An imaginary monster, especially one invoked to frighten children; a hobgoblin.
Origin
Early 17th century. From ancient Greek μορμώ a hideous female monster (also as proper noun, and as an exclamation to frighten children), perhaps cognate with classical Latin formīdāre.
Definition of mormo in US English:
mormo
nounˈmɔːməʊ
rare, historical
An imaginary monster, especially one invoked to frighten children; a hobgoblin.
Origin
Early 17th century. From ancient Greek μορμώ a hideous female monster (also as proper noun, and as an exclamation to frighten children), perhaps cognate with classical Latin formīdāre.