Synonyms of formidable

1 Syllable

high, ter, grim, dire

2 Syllables

toucher, parlous, upstream, fearful, dismaying, hard-won, fierce, grimmer, daunting, knottier, frightful, arduous, grimmest, dreadful, awful, shocking, knotty, mondo, feared, grabber, whaler

3 Syllables

tremendous, jeopardous, terrible, terrific, frightening, fearsome, difficult, appalling, liverish, dangerous, onerous, sobering, hardnosed, menacing, heightened, imposing, sky-scraping, threatening, horrific

4 Syllables

dangersome, impregnable, awesome, difficile, redoubtable, unamusing, overtaxing, reticular

5 Syllables

intimidating