PROTON

[pro.ton] n [Gk proton, neut. of protos first--more at prot-] (1920): an elementary particle that is identical with the nucleus of the hydrogen atom, that along with neutrons is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673E-24 gram -- pro.ton.ic adj