berceuse

from WordNet (r) 3.0 (2006)

berceuse
    n 1: a quiet song intended to lull a child to sleep [syn:
         {lullaby}, {cradlesong}, {berceuse}]

from The Collaborative International Dictionary of English v.0.48

Berceuse \Ber`ceuse"\, n. [F.] (Mus.)
   A vocal or instrumental composition of a soft tranquil
   character, having a lulling effect; a cradle song.
   [Webster 1913 Suppl.]