Longman Dictionary of Contemporary English homepage

Date: 1900-2000
Origin: radium

radon

noun
     
Related topics: Elements
ra‧don [uncountable]
HCE a radioactive gas that is used in the treatment of diseases such as cancer. It is a chemical element: symbol Rn

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary