Learn how to say Rightfulness correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word rightful:
having a legitimate right to property, position, or status:
the rightful owner of the jewels
legitimately claimed; fitting:
they are determined to take their rightful place in a new South Africa
Old English rihtful ‘upright, righteous’ (see right, -ful). The notion of ‘legitimacy’ dates from Middle English