Dietitian Or Nutritionist What does M.S., R.D. and L.D. mean? By Joanne Larsen 0 3381 Facebook Twitter Google+ Pinterest WhatsApp What does M.S., R.D. and L.D. mean? MS = Masters of Science, RD = Registered Dietitian and LD = Licensed Dietitian which is required in almost all states for people who provide nutrition or dietetic services