Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

Rupert's drop

noun Ru·pert's drop \ ˈrüpərts- \

Definition of Rupert's drop

: 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

There's more!

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.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!
Already a subscriber? Log in.

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).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

Ask the Editors

Word Games