What does radioactivity mean?

Definitions for radioactivityˌreɪ di oʊ ækˈtɪv ɪ ti

Here are all the possible meanings and translations of the word radioactivity.

Princeton's WordNet

  1. radiation, radioactivity(noun)

    the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay


  1. radioactivity(n.)

    a form of instability which is a property of the atomic nuclei of certain isotopes, which causes a spontaneous change in the structure of the nucleus, accompanied by emission of energetic radiation. The radiation emitted is usually sufficient to cause ionization in matter through which it passes, and is therefore called ionizing radiation. The radiation emitted by most radioactive substances is one of three types: alpha rays, beta rays, or gamma rays. Some chemical elements have no stable isotopes, and these are referred to as radioactive elements, and the element itself is said to possess radioactivity. The changes in radioactive nuclei which cause radiation in most cases cause the chemical identity of the nucleus itself to change, as when tritium (an isotope of hydrogen) emits a beta ray and converts to helium. The radioactive decay process is a first-order reaction, and the rate of decay of a particular isotope can therefore be expressed as the half life of the isotope, which is the time it takes for one half of the remaining undecayed isotope to decay, and is a constant independent of the proportion of original material which has already decayed. The half life of tritium, for example, is 12.3 years.


  1. radioactivity(Noun)

    Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus.

  2. radioactivity(Noun)

    The radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc.


  1. Radioactivity

    "Radioactivity" is a song written by Ralf Hütter, Florian Schneider and Emil Schult, and recorded by electronic band Kraftwerk as the title track of its 1975 album Radio-Activity.

U.S. National Library of Medicine

  1. Radioactivity

    The spontaneous transformation of a nuclide into one or more different nuclides, accompanied by either the emission of particles from the nucleus, nuclear capture or ejection of orbital electrons, or fission. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)


  1. Chaldean Numerology

    The numerical value of radioactivity in Chaldean Numerology is: 9

  2. Pythagorean Numerology

    The numerical value of radioactivity in Pythagorean Numerology is: 3

Sample Sentences & Example Usage

  1. David Brenner:

    Radioactivity has a half-life, it does simply decay away in roughly a day or two.

  2. Yves Marignac:

    A scenario which leads to water loss by damage to the pools could lead to a release of radioactivity of the same or higher order than a core meltdown.

  3. Chuck Schumer:

    While inspectors would likely be able to detect radioactive isotopes at a site after 24 days, that delay would enable Iran to escape detection of any illicit building and improving of possible military dimensions( PMD) - the tools that go into building a bomb but don't emit radioactivity.

  4. Kai Vetter:

    Even if some of the radioactive materials 'leaked' or still 'leak' from the ship, this radioactivity will be diluted very quickly in the water reducing the concentration substantially, in addition, the radiation emitted by the radioactive materials on the ship will not travel very far as the water is an excellent shield.

Images & Illustrations of radioactivity

  1. radioactivityradioactivityradioactivity

Translations for radioactivity

From our Multilingual Translation Dictionary

Get even more translations for radioactivity »


Find a translation for the radioactivity definition in other languages:

Select another language:

Discuss these radioactivity definitions with the community:

Word of the Day

Would you like us to send you a FREE new word definition delivered to your inbox daily?

Please enter your email address:     


Use the citation below to add this definition to your bibliography:


"radioactivity." Definitions.net. STANDS4 LLC, 2018. Web. 23 Mar. 2018. <https://www.definitions.net/definition/radioactivity>.

Are we missing a good definition for radioactivity? Don't keep it to yourself...

Nearby & related entries:

Alternative searches for radioactivity:

Thanks for your vote! We truly appreciate your support.