dustaram

formidable — SB 4.31.7

insurmountable — SB 1.1.22, SB 4.10.30

the formidable foe — SB 3.18.27

insurmountable — SB 2.7.42, Madhya 6.235

very difficult to surmount — SB 8.12.39

very difficult to cross for one without a son — SB 6.14.56

very dangerous — SB 4.10.29

which is very difficult to cross — SB 10.2.31