1the hard woody covering around the kernel of a nut.
2 (nut shell) any of a number of bivalve molluscs occurring chiefly in cool seas, in particular:
a small oval-shelled bivalve (genus Nuculana, family Nuculanidae).a bivalve with a rectangular shell which is rounded at the front and angled behind (genus Nucula, family Nuculidae).
Phrases
in a nutshell
in the fewest possible words: she put the matter in a nutshell
