PMS is a three-letter initialism which may mean: · Premenstrual syndrome, a collection of physical, psychological and emotional symptoms related to a woman's menstrual cycle · Postmarketing surveillance · Pantone Matching System, a colour space · P.M.S. Hacker, a British philosopher · Prime Minister's Spokesman · PMS Clan, Pandora's Mighty Soldiers, an all-female gaming clan · Philips Medical Systems, a division of the electronics company Philips · Property management system, software designed to manage many aspects of hotel operations · POS management system (Point of sale management system) · power management system (such as Cool'n'Quiet and SpeedStep) · Pre-main sequence star, in astronomy, is a star that has not yet reached the main sequence · Pretty Mean Sisters, a stable in the World Wrestling Federation · Professor of Military Science,