In sociology, trust is willing acceptance of one person's power to affect another. It is discussed more formally in the articles on social capital, profession and authority. There is much dispute on whether degrees of trust can be measured, or whether it simply exists until there is doubt. See ethics and meta-ethics for more on these abstract questions. There is also much dispute about how lying, blaming and hypocrisy interact with trust. See also distrust
A Trust company is a near-bank: a financial institution offering banking, investment and estate administration services.
A trust is a legal arrangement for the ownership of property on behalf of another.
Trust is an important concept in computer security and security engineering. In this sense, a 'trusted' resource is one that you are forced by necessity to trust - that is to say, that its failure will compromise the security or integrity of the system.
In cryptography, trust is either of two related concepts - how much one trusts another person to introduce keys, and how confident one is that a given key has a given owner. These determinations are often made via a web of trust.