Meaning of the Sanskrit Word: pitrn

  pitrn—forefathers    SB 3.3.26, SB 4.27.11
  pitrn—the forefathers    SB 3.32.2, SB 3.32.17
  pitrn—to ancestors    Bg 9.25
  pitrn—fathers    Bg 1.26
  pitrn—unto the forefathers    SB 7.14.15
  pitrn—the residents of the Pitrloka    SB 2.3.8
  pitrn—about the denizens of the Pitrloka planet    SB 1.16.31
  pitrn—the Pitas    SB 6.6.19

Can't find any compound Sanskrit words containing pitrn.