G5 is a two character combination which may refer to any of many items, classifications, and entities: Groups and organizations · G5 countries, the "Group of Five" countries: France, Germany, Japan, the United Kingdom, and the United States, superseded by the G8 · G5 group, former group of the largest European countries: France, Germany, Italy, the United Kingdom, and Spain, now expanded to G6 · G5, a group of British universities consisting of Oxford, Cambridge, University College London, London School of Economics and Imperial College · Assistant Chief of staff , Public Affairs (military shorthand) · G5 also refers to the 5th floor of a dormitory, Gladden House, that sits on the the northwest end of the Williams College campus in Williamstown, MA. The fifth floor of the dormitory is "pants optional". · G5 is the IATA code for China Express Airlines S