What is "gostautai"

Goštautai (Lithuanian plural form), masculine Goštautas and feminine form Goštautaitė ( Polish original, after Kasper Niesiecki - Gastoldowie, later transformed into Gasztołdowie) were a Lithuanian noble family, one of the most influential magnate families during the 15th and early 16th centuries. Their only serious rivals were the Kęsgailos, and from the end of the 15th century the fast rising in power and influence Radziwiłł family clan. It appears from the Latin original spelling of their name Gastoldus which is a variation of castaldius that they had been close to the Grand Dukes and that their function was to oversee ducal demesne. Most power family gained during the reign of Casimir Jagiellon. The castaldius of Vytautas, Andrius Goštautas might have been a voivode of Vilnius and Kreva, and father of Jonas, appears to have been the precursor of the family growth. The majority of the family's possessions (lands) were in the western part of the Duchy and eastern ethnic Lithuania. After the death of the last scion of the family, Stanislovas Goštautas, the Polish King and Grand Duke of Lithuania Sigismund II Augustus inherited his possessions as a matter of right, per Grand Duchy of Lithuania law.