Froglike

Though it was not far to Jamiltepec, once outside the village, the chauffeur and his little attendant lad began to get frightened, and to go frog-like with fear.

Source: wiktionary

I have seen, too, a frog-like beast with protruding green eyes, which is simply a gaping mouth with a huge stomach behind it.

Source: wiktionary

a froglike croak

Source: wiktionary

Parsons, Winston's fellow-tenant at Victory Mansions, was in fact threading his way across the room--a tubby, middle-sized man with fair hair and a froglike face.

Source: wiktionary