n.
A gas-filled device in which the path of charged subatomic particles can be detected by the formation of chains of droplets on ions generated by their passage. It is also used to infer the presence of neutral particles and to study certain nuclear reactions.
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.