What term describes the oldest son appointed by the will of his deceased father to settle the estate?

The term that describes the oldest son appointed by the will of his deceased father to settle the estate is "Executor." An executor is a person named in a decedent's will who is responsible for administering the estate according to the terms set forth in the will and ensuring that the deceased’s wishes are carried out. This includes tasks such as paying debts, distributing assets, and filing necessary documents with the court.

In the context of estate settlement, the executor has a fiduciary duty to act in the best interest of the estate and its beneficiaries. This role is often a significant responsibility, as it requires careful attention to legal and financial matters.

The other options, while related to estate management, do not fit the specific role defined in the question. A trustee is typically appointed to manage a trust, an administrator generally refers to someone appointed by the court to manage an estate when there is no will, and a beneficiary is an individual who receives assets from an estate but does not have any administrative responsibilities. The distinct role of the executor highlights the importance of fulfilling the deceased's wishes and maintaining the integrity of the estate's settlement process.