Definition of Sextuple

What is the meaning of the term Sextuple in the world of football? When was it first used?

Barcelona FC winger, Neymar Junior, coined the term sextuple when talking to reporters about repeating the feat his club achieved in 2014/15 season when they won the treble. Barcelona won the domestic league, Spanish Cup and the UEFA Champions League in that season.

It would be quite something if Barca did manage to win the sextuple.