Definition of "proton" [proton]

• A stable, positively charged subatomic particle in the baryon family having a mass 1,836 times that of the electron. See Table at subatomic particle. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Long-term proton pump inhibitor therapy and risk of hip fracture."
• "One proton is just like another; but sodium and chlorine are distinct because of the number and arrangement of these parts."
• "Taking away or adding just one proton from the nucleus of an element would turn it into a completely different element with completely different properties."