This is the 11762nd most frequent Russian word.
заинтересованность
Interest or engagement.
The word 'заинтересованность' refers to 'interest' or 'engagement' one shows towards a subject.
Он проявил заинтересованность в этом проекте.
He showed interest in this project.
Here, 'заинтересованность' indicates an emotional or involved concern in something significant.
У родителей была большая заинтересованность в успехах их детей.
The parents had a great interest in their children's achievements.
In this case, 'заинтересованность' conveys the engagement and proactive attitude of a group.