WordNet sense 1 (a radioactive transuranic element synthesized by bombarding einsteinium with alpha particles (Md is the current symbol for mendelevium but Mv was formerly the symbol)):

mendelevium, mV

WordNet sense 2 (a licensed medical practitioner):

doc, doctor, physician, Dr., medico

WordNet sense 3 (a Mid-Atlantic state; one of the original 13 colonies):

Maryland, Old Line State, Free State

WordNet sense 4 (a doctor's degree in medicine):

Doctor of Medicine