Halidron Collider Details - PDF file from CERN
An excerpt from the above file:
LHC stands for Large Hadron Collider. Large due to its size(approximately 27 km in circumference), Hadron because it acceleratesprotons or ions, which are hadrons, and Collider becausethese particles form two beams travelling in opposite directions,which collide at four points where the two rings of the machineintersect.Hadrons (from the Greek ‘adros’ meaning ‘bulky’) are particlescomposed of quarks. The protons and neutrons that atomic nucleiare made of belong to this family. On the other hand, leptons areparticles that are not made of quarks. Electrons and muons areexamples of leptons (from the Greek ‘leptos’ meaning ‘thin’).