A hadron is any particle made of quarks and gluons. Hadrons include mesons, which are quark doublets, and baryons (such as the proton and neutron), which are quark triplets. Hadrons can interact via the strong force. Although they have no overall strong charge (i.e., they are strong charge neutral objects) they take part in residual strong interactions due to the strong charges of their constituents.
The name 'hadron' comes from the Greek for 'thick and bulky' and was coined by the Russian physicist L. Okun in 1962.