The Collaborative International Dictionary of English v.0.48:

Shawm \Shawm\, n. [OE. shalmie, OF. chalemie; cf. F. chalumeau
   shawm, chaume haulm, stalk; all fr. L. calamus a reed, reed
   pipe. See Haulm, and cf. Calumet.] (Mus.)
   A wind instrument of music, formerly in use, supposed to have
   resembled either the clarinet or the hautboy in form.
   [Written also shalm, shaum.] --Otway.
   [1913 Webster]

         Even from the shrillest shaum unto the cornamute.
                                                  --Drayton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

shawm
    n 1: a medieval oboe