hadron Group of subatomic particles that are influenced by strong nuclear force. Made up of quarks, the group can be divided into baryons, such as the neutron and proton, and mesons. More than 150 hadrons have been discovered, and, with the exception of the proton and antiproton, they are all unstable. Unlike leptons, they have a measurable size.

had·ron / ˈhadˌrän/ • n. Physics a subatomic particle of a type including the baryons and mesons that can take part in the strong interaction.DERIVATIVES: ha·dron·ic / hadˈränik/ adj.