What Is Sadame? From Saint Beast's Kizuna&sadame.

Sadame means decision or law, regulation etc.
It means "something that has been determined" so it can mean "fate" or "destiny", which are believed to be "pre-determined"
Then  Kizuna & Sadame means "Friendship", "Bonds", "Ties" "Family tie" & "Destiny" "Fate"

In brief, could be: 
Kizuna & Sadame =  "Friendship"/ "Bonds" & "Destiny" /"Fate"