Synonyms of decisively

2 Syllables
really, doubtless, truly
3 Syllables
exactly, surely, finally, easily, actually
4 Syllables
adamantly, precisely, decidedly
5 Syllables
conclusively, irrevocably, unambiguously, resolutely, emphatically, absolutely, unquestionably, positively, definitely
6 Syllables
categorically, definitively, unconditionally