Wiktionary
n. (context legal English) In the law of wills, the death of two persons, each of whom would inherit the estate of the other if deemed to have survived the other, where such deaths occur within a time period set by statute (typically 120 hours), because of which the law treats each person as if they had died before the other in determining the distribution of estates.
Wikipedia
Simultaneous death is a problem of inheritance which occurs when two people, at least one of whom is entitled to part or all of the other's estate on their death (usually a husband and wife) die at, or very near, the same time. This is usually the result of an un-natural death occurring from events such as an accident, a homicide, or a murder-suicide.
Under the common law, if there was any evidence whatsoever that one party had survived the other, even by a few moments, then the estates would be distributed in that order, though the decedents could write (or have written) a clause in the will that requires their property to be distributed as though each had predeceased the other.
Some wills now include Titanic clauses (named for the RMS Titanic, which caused many simultaneous deaths among testators and executors). These clauses lay out explicit instructions for dealing with simultaneous death.
Usage examples of "simultaneous death".
I suspect that if one were to meditate long enough on the lotus, the idea of simultaneous death and rebirth would occur to one.
A greater empathy the controller had was for his permanent, simultaneous death as the guardian processed him.
Though they will not kill nearly as many of your people as you do on your own, we realize that the simultaneous death of small groups is perceived to be more tragic than a very large mortality stretched over time and space.
In the event of the simultaneous death of both dragon and contestant, the dragon will be deemed the winner.