Definition of "childishness"
noun
countable and uncountable, plural childishnesses
(countable) Childish behaviour.
Quotations
Exorcism, unction, the sign of the cross, holy water, infant-communion, and many other childishnesses, were also called "Apostolic institutions" — not at first, but long after they were invented, to conceal their real origin […]
1868, John Mockett Cramp, Baptist History: from the foundation of the Christian church to the close of the eighteenth century, page 43