Assumption of and reliance on the honesty of another party.
If you trust someone then you believe that they’re honest and reliable. If you loan your car to someone, you had better trust them to bring it back to you, and in good shape.
Trust takes many forms. You could trust in something abstract, like the idea that things happen for a reason. If you are naïve, people might take advantage of your trust. A trust can also be a fund or an alliance meant to take care of something. A trust fund gives money to some lucky trustee so that he doesn’t need to worry about employment. A wildlife trust saves land from development so animals can live there.