Hear a word and type it out. How many can you get right?

TAKE THE QUIZ# Planck's constant

## noun

variants
or less commonly Planck constant

**:**a constant that gives the unvarying ratio of the energy of a quantum of radiation to its frequency and that has an exact value of 6.62607015 × 10

^{−34}joule seconds —symbol

*h*

Love words? Need even more definitions?

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

Merriam-Webster unabridged
## Share