Synonyms of collectively

2 Syllables
jointly
3 Syllables
combined, agreeingly, alike, mutually, conjointly, agreeably, together
4 Syllables
altogether, concertedly, concorantly, consensually, similarly, communally, synchronously, accordingly, unitedly, concurrently, connectedly, harmoniously
5 Syllables
undisputedly, simultaneously, companionably, coincidentally, concomitantly, inextricably, inseparably, intimately, reciprocally, synchronically, unanimously
6 Syllables
contemporaneously, cooperatively