1. To resolve a conflict or disagreement by using diplomacy, charm, or reconciliation; to make a tense situation more peaceful
After the argument, she tried to smooth things over by apologizing sincerely.
Depois da briga, ela tentou aplanar as coisas pedindo desculpas sinceras.
2. To make a difficult situation less problematic or uncomfortable through peaceful negotiation
The manager smoothed things over between the two conflicting employees.
O gerente resolveu a situação entre os dois funcionários em conflito.