Concisely, in a few words, as in Here's our proposal—in a nutshell, we want to sell the business to you. This hyperbolic expression alludes to the Roman writer Pliny's description of Homer's Iliad being copied in so tiny a hand that it could fit in a nutshell. For a time it referred to anything compressed, but from the 1500s on it referred mainly to written or spoken words.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.