RSM

abbreviation for

regimental sergeant major
Royal School of Music
Royal Society of Medicine

San Marino (international car registration)

Word Origin for RSM

(sense 4) From R(epublic of) S(an) M(arino)

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012