Synonyms of 'formidable'

appalling, arduous, astonishing, astounding, awesome, awful, brutal, burdensome, challenging, complex, conspicuous, critical, delicate, demanding, difficile, difficult, dire, direful, dread, dreadful, earnest, effortful, egregious, exacting, exceptional, extraordinary, fabulous, fantastic, fatal, fateful, fell, abstruse, freaky, frightful, ghastly, grave, grim, grisly, gruesome, hairy, hard, heavy, herculean, hideous, horrendous, horrible, horrid, horrific, imposing, impressive, incredible, indomitable, intricate, knotted, knotty, labored, laborious, macabre, marked, marvelous, mean, mighty, morbid, notable, noteworthy, noticeable, onerous, operose, outstanding, overwhelming, portentous, powerful, prodigious, redoubtable, remarkable, rigorous, rough, rude, rugged, serious, severe, shocking, signal, sober, solemn, spiny, steep, strenuous, striking, superior, terrible, terrific, thorny, ticklish, toilsome, tough, tremendous, tricky, unbelievable, uncommon, uphill, weighty, wicked, wonderful