Mid 16th century. Origin unknown; perhaps related to mum, although this would present phonological difficulties. Apparently not related to French môme little child.
mome2
/məʊm/
nonce-wd.
adjective
Explained by Carroll as: grave, solemn. (Only in Carroll and later allusions.).
Origin
Mid 19th century; earliest use found in ‘Lewis Carroll’ (1832–1898), author, mathematician, and photographer (real name Charles Lutwidge Dodgson). A factitious word introduced by Lewis Carroll.