And ortography: Ó <--> O; IÓ <--> IE, Ó <--> A
ósmy - osiem - 8th - 8
siódmy - siedem - 7
szósty - sześć - 6
zawrócić - zawracać - turn back
But there is a lot more, because e.g. dwunasty - dwanaście = 12 or dwudziesty - dwadzieścia =20; dwusetny - dwieście = 200. It's remainder after dual form in Polish.
Children want to make U and Ó one letter :) Personally I think that we have more words that have uninflected Ó than inflected.
It doesn't completely fit here, but it wouldn't fit anywhere else, so I just ask this here. How do I say for exemple: "This is your dog, (Sir)." Is there different possessive pronouns for the formal way, or would this be still just "To jest twój pies." or in third person "To jest jego/jej/ich pies?"