“positron emission”

We have one entry that includes the term positron emission.

positron-emission tomography

noun

: tomography in which a cross-sectional image of regional metabolism is obtained by a usually color-coded representation of the distribution of gamma radiation given off in the collision of electrons in cells with positrons emitted by radionuclides incorporated into metabolic substances that have been administered (as by injection)

See the full definition

Word of the Day

Listen to the pronunciation of superfluous

See Definitions and Examples »

Test Your Vocabulary

Face Your Fears

  • clown-mask
  • Arachnophobia is the fear of what multi-legged creatures?
Spell It

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

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
boy-thinking-light-bulb
Quiz: Are You An Idiom Savant? Figure out what these figures of speech actually ...