Synonyms of tremendous

1 Syllable
high, vast, great, big, blimp
2 Syllables
heftier, bigger, huger, moby, monstrous, king-size, jumbo, hugest, dreadful, awful, mondo, greatest, massy, mammoth, whaling, boundless, whopper, vastest, whale, massiest, biggest, vaster, cracking, frightful, spread-out, hulking, super, massier, large, hefty, fearful, whopping, buller
3 Syllables
hellacious, deafening, enormous, gigantic, prodigious, stupendous, colossal, marvelous, pythonic, ballbuster, ginormous, sizeable, terrible, terrific, fantastic, humongous, towering, appalling, gargantuan, stretched-out, titanic, immense, massive, towery, amazing, astounding, fearsome, humungous, cyclopean, walloping, excellent, wonderful, sky-scraping, fabulous
4 Syllables
incredible, awesome, astronomic, exceptional, formidable, larger-than-life, monumental, super-duper, bunyanesque, brobdingnagian, gigantesque, mastodonic, large-scale
5 Syllables
super-colossal, extraordinary, astronomical