Ma'anar ƙamus na "heavy hydrogen" yana nufin isotope hydrogen wanda ke da neutron guda ɗaya baya ga proton da aka saba samu a cikin hydrogen na al'ada. Wannan isotope kuma ana kiransa da deuterium, kuma yana da babban adadin atomic fiye da hydrogen na al'ada. Ana amfani da hydrogen mai nauyi a aikace-aikacen kimiyya daban-daban, gami da kimiyyar nukiliya, sunadarai, da ilmin halitta.
