proton
pro.ton \'pro--.ta:n\ \pro--'ta:n-ik\ n [Gk pro-ton, neut. of pro-tos first - more at PROT-] : an elementary particle that is identical with the nucleus of the hydroge n atom, that along with neurons 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 1.672X10-24 gram - pro.ton.ic aj