Not necessarily
Definition 1 of 1
Pro Tip 1/3Context Matters
Understand the scenario to grasp why 'not necessarily' is used, as it often challenges assumptions. 
He’s wealthy but not necessarily happy.
Pro Tip 2/3Uncertainty
'Not necessarily' implies that there’s a possibility something else could be true or happen. 
This rule doesn’t necessarily apply to every case.
Pro Tip 3/3Softening Disagreement
Use it to gently disagree or express a differing opinion without being too direct. 
That’s one solution, but not necessarily the best one.