Top Definition
The antimatter equivalent of a proton. It has the same mass as a proton, but opposite charge (negative).
When a proton and antiproton orbit each other, they make protonium. When an antiproton and electron orbit a helium nucleus, they make antiprotonic helium.
by Pie Stealer October 27, 2015

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from We'll never spam you.