durgama
durgama — invincible; CC Madhya 16.270
kaṇṭaka-durgama — difficult to traverse because of thorns; CC Madhya 17.222
su-durgamā — difficult to understand; CC Madhya 23.40
durgama — difficult to understand; CC Antya 5.21
durgama — very, very difficult; CC Antya 5.104-105
durgama — difficult; CC Antya 12.71
su-durgamā — difficult to understand; CC Antya 19.105