Corpus is the Latin for body and in terms of estate planning a trust corpus refers to the body of the trust. Whatever amount the trust is funded with is considered the corpus. It is the amount of money that will produce income for the beneficiary. When defined in the law of estate planning the corpus of the estate is the amount of property left by a person when they pass away. Estate planners use the term corpus when writing last wills and testaments and when setting up trust funds in order to abide by the laws of the courts and follow protocol established. Defining the corpus of the trust or the estate in detail is vital to assuring the last wishes are carried out in their fullest.