Rupert's drop

noun Ru·pert's drop \ˈrüpərts-\

Definition of Rupert's drop

  1. :  a congealed blob of glass formed by dropping melted glass into water and setting up such residual stresses that the globule explodes violently when the surface is scratched or a piece broken off

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Join MWU now and get access to America’s largest dictionary, with:

  • 300,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Origin and Etymology of rupert's drop

after Prince Rupert of Germany †1682 who first brought it to England to his uncle Charles I of England

Seen and Heard

What made you want to look up Rupert's drop? Please tell us where you read or heard it (including the quote, if possible).


a trip made at another's expense

Get Word of the Day daily email!