Sextuplet
A group of six notes occupying the time of four.
Sfogato (It.) (sfo-gah'-to) [from sfogare, to evaporate]. A soprano voice of thin, light quality and unusually high range is called a soprano sfogato.
A Sforzando (It.) (sfortz-an'-do) or Sforzato, abbreviated Sf. or Sfz. Forced." A strong accent immediately followed by piano.