Meaning of the Sanskrit Word: vainyasya

  vainyasya—of Mahārāja Pṛthu, the son of Vena    SB 4.15.9-10
  vainyasya—of the son of King Vena (Pṛthu Mahārāja)    SB 4.20.34
  vainyasya—of the son of Mahārāja Vena    SB 4.23.37

Can't find any compound Sanskrit words containing vainyasya.