boyism
/ˈbɔɪɪz(ə)m/noun
1A boyish or childish characteristic or mannerism (especially in a literary work); an instance of boyishness.
2The characteristic nature of a boy; boyishness, childishness.
Origin
Early 18th century; earliest use found in John Dryden (1631–1700), poet, playwright, and critic. From boy + -ism.