doh

from WordNet (r) 3.0 (2006)

doh
    n 1: the syllable naming the first (tonic) note of any major
         scale in solmization [syn: {do}, {doh}, {ut}]

from The Collaborative International Dictionary of English v.0.48

doh \doh\ (d[=o]), n.
   the syllable naming the first (tonic) note of any major
   diatonic scale in solmization, usually written {do}.

   Syn: do, ut.
        [WordNet 1.5]