I think it's Upamon for both the dub and the anime. And it's "Oikawa", not "Owikawa".
Words so far:
Omegamon
Ogremon
Omnimon
Ookuwamon
Omekamon
Ophanimon
Option Card
Otomamon
Ogudomon
Owikawa (sp?)
Opamon (Armadilamon's training) (<--It was Upamon, or was that just the dub)
Olympian 12
Omega...