Meaning of the Sanskrit Word: mahiyasam

  mahīyasām—of the great personalities, devotees    Madhya 22.53, Madhya 25.85
  mahīyasām—of the greatest    SB 1.19.30
  mahīyasām—of the most powerful    SB 4.5.5
  mahīyasām—among other great personalities    SB 6.15.10
  mahīyasām—of the great souls (the mahātmās, or devotees)    SB 7.5.32

Can't find any compound Sanskrit words containing mahiyasam.