radioactivity

noun ra·dio·ac·tiv·i·ty \ ˌrā-dē-ō-ak-ˈti-və-tē \
Updated on: 15 Nov 2017

Definition of radioactivity

: the property possessed by some elements (such as uranium) or isotopes (such as carbon 14) of spontaneously emitting energetic particles (such as electrons or alpha particles) by the disintegration of their atomic nuclei; also : the rays emitted

Recent Examples of radioactivity from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'radioactivity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of radioactivity

International Scientific Vocabulary


RADIOACTIVITY Defined for Kids

radioactivity

noun ra·dio·ac·tiv·i·ty \ ˌrā-dē-ō-ak-ˈti-və-tē \

Definition of radioactivity for Students

1 : the giving off of rays of energy or particles by the breaking apart of atoms of certain elements (as uranium)
2 : the rays or particles that are given off when atoms break apart

Medical Dictionary

radioactivity

noun ra·dio·ac·tiv·i·ty \ -ak-ˈtiv-ət-ē \

medical Definition of radioactivity

plural radioactivities
: the property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of their atomic nuclei


Seen and Heard

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

Love words? Need even more definitions?

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

WORD OF THE DAY

to remove or wipe out

Get Word of the Day daily email!

Test Your Vocabulary

Find the Cousins

  • a-large-tree-with-many-branches
  • Which pair shares a common word ancestor?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ

Love words? Need even more definitions?

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