Meaning of the Sanskrit Word: nirmatsaranam

  nirmatsarāṇām—of the one-hundred-percent pure in heart    SB 1.1.2, Adi 1.91, Madhya 25.149
  nirmatsarāṇām—of the fully pure in heart    Madhya 24.100

Can't find any compound Sanskrit words containing nirmatsaranam.