Lacking adult maturity or experience; immature: a callow young man. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "callow" in a sentence
"(Being a new anonymous:) I have nothing at all to say about Kate DiCamillo as a person, but agree that her work is often heavy-handed, condescending, uninteresting, and just plain callow."
"This is hardly triumphalism, but calling a callow frat boy out on his bullshit."
"He suddenly recalled a callow boy telling his tutor that he dreaded the sea voyage home, because he would have to be among common men rather than thoughtful acolytes like himself."