A toy consisting of a clownlike puppet that springs out of a box when the lid is activated.(noun)
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 "jack-in-the-box" in a sentence
"I think a middle-aged man with a big paunch straddling a motorcycle looks like a jack-in-the-box before it springs—all rolled up in himself."
"Thomas Mugridge popped out of his galley like a jack-in-the-box."
"He is a jack-in-the-box the way he pops into the chair."