bolthead

[ bohlt-hed ]

/ ˈboʊltˌhɛd /

the head of a bolt.

Chemistry. (formerly) a matrass.

Nearby words

late Middle English word dating back to 1425–75; see origin at bolt¹, head

Let a condensed beam be sent through a large flask or bolthead containing common air.
Fragments of science, V. 1-2|John Tyndall
If I'd 'a' called it a bolthead it would 'a' done just as well.
The Adventures of Huckleberry Finn|Mark Twain