“F2”

We have one entry that includes the term F2.

F2 layer

noun

: the upper of the two layers into which the F region of the ionosphere splits in the daytime at varying heights from about 120 miles (200 kilometers) to more than 300 miles (500 kilometers) above the earth

See the full definition

Word of the Day

Listen to the pronunciation of complaisant

See Definitions and Examples »

Test Your Vocabulary

Face Your Fears

  • clown-mask
  • Arachnophobia is the fear of what multi-legged creatures?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

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...