The Collaborative International Dictionary
Intestacy \In*tes"ta*cy\, n. [From Intestate.]
The state of being intestate, or of dying without having made
a valid will.
--Blackstone.
Douglas Harper's Etymology Dictionary
1767, from intestate + -acy.
Wiktionary
n. (context legal English) the state of being intestate, or of dying without having made a valid will
Wikipedia
Intestacy is the condition of the estate of a person who dies without having made a valid will or other binding declaration. Alternatively this may also apply where a will or declaration has been made, but only applies to part of the estate; the remaining estate forms the "intestate estate".
Intestacy law, also referred to as the law of descent and distribution, refers to the body of law ( statutory and case law) that determines who is entitled to the property from the estate under the rules of inheritance.