“first(-)order”

We have one entry that includes the term first(-)order.

first-order reaction

noun

: a chemical reaction in which the rate of reaction is directly proportional to the concentration of the reacting substance compare order of a reaction

See the full definition

Word of the Day

Listen to the pronunciation of frugal

See Definitions and Examples »

Test Your Vocabulary

Commonly Misspelled Words Vol. 2 Quiz

  • sequel spelled three ways with the incorrect ways crossed out and the correct spelling circled
  • Rachel seemed to be _____ in every endeavor she started.
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.

Pick the best words!

PLAY
Love words? Need even more definitions?

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

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
sweet smart pug puppy dog sitting in front of blackboard with chalk question marks
Commonly Confused Words Quiz Vol. 3 Do you have a (flare/flair) for choosing the righ...