Meaning of the Sanskrit Word: prthivyam

  pṛthivyām—in the earth    Bg 7.9, SB 5.12.5-6, SB 9.7.25-26
  pṛthivyām—within the universe    Bg 18.40
  pṛthivyām—within this world    SB 9.19.13

Can't find any compound Sanskrit words containing prthivyam.