1. A simultaneous or reciprocal decrease in quality, strength, value, or condition affecting two or more parties equally
The mutual decline of both companies led to their merger negotiations.
O declínio mútuo de ambas as empresas levou às negociações de fusão.
2. A shared deterioration in a relationship, agreement, or situation between parties
The mutual decline in their friendship became evident over time.
O declínio mútuo da amizade deles tornou-se evidente com o tempo.