Pinkster Monday means: An obsolete American term for Whit Monday or Pentecost Monday - the day after Pentecost Sunday. 'Pinkster' is a Dutch-derived word for Pentecost , reflecting the Dutch colonial influence in early. The word is mostly archaic or historical; you will only encounter it in old texts, period drama, or school history rather than current teen conversation. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour.