sex·tup·let 
(sĕk-stŭplĭt, sĕkstŭp′-)
(sĕk-stŭplĭt, sĕkstŭp′-)n.
1. One of six offspring born in a single birth.
2. A group or combination of six associated by common properties or behavior.
3. Music A group of six notes having the time value of four notes of the same kind.
[From SEXTUPLE (modeled on TRIPLET).]