The definition of a proton is a particle with a positive charge that is in the nucleus of an atom.(noun)
An example of a proton is the single proton in the nucleus of a hydrogen atom.
See proton in Webster's New World College Dictionary
Origin: ModL < Gr prōton, neut. of prōtos, first: see proto-
See proton in American Heritage Dictionary 4
noun Abbr. p
Origin: From Greek prōton
Origin: , neuter of prōtos, first; see per1 in Indo-European roots.
Learn more about proton