Synonyms of boo

1 Syllable
scoff, pooh, oop, ugh, ah, hoot, um, hiss, er, ums, ers, huh, whoop, psst, phooey
2 Syllables
hooray, hissed, catcall, oh's, egad, hissing, whooped, hooted, ahem, scoffed, jeepers, hooting
4 Syllables
disapproval, sibilate, interjections, sibilance, interjection