Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

Medical Dictionary

catalyst

play
noun cat·a·lyst \ˈkat-əl-əst\

Medical Definition of catalyst

  1. :  a substance (as an enzyme) that enables a chemical reaction to proceed under different conditions (as at a lower temperature) than otherwise possible





Seen and Heard

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

WORD OF THE DAY

February 7, 2016

a slight offense

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image1037863653

Which of the following refers to thin, bending ice, or to the act of running over such ice?

spindrift pince-nez kittly-benders duvet
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ