Relating to a will or other document effective at death.
A testator (/tɛsˈteɪtɔːr/) is a person who has written and executed a last will and testament that is in effect at the time of their death. It is any "person who makes a will."
English
Etymology
From Middle English testamentarie, from Anglo-Norman testamentarie and Latin testāmentārius (“of or belonging to wills”).