MALMSEY is a 7 letter word that starts with M.
\Malm"sey\, n. [OE. malvesie, F. malvoisie, It. malvasia, malavagia, fr. Malvasia, or Napoli di Malvasia, in the Morea.] A kind of sweet wine from Crete, the Canary Islands, etc. --Shak.
WordNet Dictionary