Codicil: 
A small amendment to a will that makes a minor change.

Elective share: 
The share provided by state law to the spouse and children of the deceased. Usually this is a dollar figure that is paid to the survivors before any other bills or bequests are doled out.

Executor: 
The person who closes an estate. (If the executor is a woman, she is sometimes called the executrix.)

Guardian:
The individual left in charge of caring, feeding and educating the dependent(s) of the deceased. Most often, the surviving parent becomes the guardian of the children's person and property. All guardians are subject to court approval. 

Intestate or Intestacy:
Dying without a will.

"Per stirpes" is a Latin phrase meaning: 
If a child dies before the parent, that child's children split the share.

Probate estate:
Property exclusively belonging to the deceased. Shared property (such as a joint checking account) is not included. The payoff from a life insurance policy is not usually considered part of the probate estate.

Renouncing the will:
A person may decide not to accept the inheritance left to them in a will, and instead take a share of the estate as provided by the law. 

Testate: 
Dying with a will.

Testator:
The person who has written the will.

Trustee: 
The executor of a trust.

Trust:
A legal arrangement in which an individual gives control of assets or capital to another person.

Will:
A legal document which indicates how a person wants their belongings to be distributed after their death. A will can also express how a person wants themselves and their property to be taken care of should they become incapacitated.