quantum chromodynamics: a theory of strong interactions between elementary particles (including the interaction that binds protons and neutrons in the nucleus); it assumes that strongly interacting particles (hadrons) are made of quarks and that gluons bind the quarks together
knowledge domain: the content of a particular field of knowledge
epiphysis: the end of a long bone; initially separated from the main bone by a layer of cartilage that eventually ossifies so the parts become fused