Meaning of the Sanskrit Word: upasrtanam

  upasrtanam—of those who have taken complete shelter    SB 5.9.20
  upasrtanam—the devotees who have taken shelter at Your lotus feet    SB 6.9.43
  upasrtanam—of the devotees    SB 8.12.47

Can't find any compound Sanskrit words containing upasrtanam.