97 synonyms for really such as is that so, actually, assuredly, assuredly, go on, and is that a fact. Really is an adverb, and its antonyms are dubiously and questionably.
Actually, as a matter of fact, if truth be told, in actual fact, in actuality, in fact, in point of fact, in reality, in sooth, in truth, and to tell the truth.
Assuredly, certainly, genuinely, honestly, indeed, indubitably, surely, truly, undeniably, undoubtedly, unquestionably, verily, and without a doubt.
Assuredly, awful, awfully, bitching, certainly, dead, decidedly, devilish, devilishly, downright, dreadfully, eminently, ever so, exceeding, exceedingly, exceptionally, extraordinarily, extremely, fair, fearfully, frightfully, genuinely, heartily, honestly, immensely, indeed, indubitably, jolly, lekker, majorly, mega, mighty, most, mucho, oh-so, plumb, positively, powerful, quite, real, remarkably, right, seriously, sore, stinking, surely, terribly, terrifically, thoroughly, too … for words, très, tremendously, truly, ultra, unco, uncommonly, undeniably, undoubtedly, unquestionably, verily, very, way, well, and without a doubt.
Go on, go to, is that a fact, is that so, well I never, well I never did, well I'll be blowed, and you don't say.