Definition of schoolboyish in US English:

schoolboyish

adjective

  • Resembling or characteristic of a schoolboy; schoolboy-like.

Origin

Late 18th century; earliest use found in Thomas Twining (bap. 1734, d. 1804), classical scholar and translator. From schoolboy + -ish.

Pronunciation

schoolboyish

/ˈskuːlbɔɪɪʃ/