- Often abbreviated "ToD".
The "Time of (an enemy's) Death," or defeat and disappearance from the screen. Combined with knowledge of the Respawn Time, ToD may be used to obtain a rough estimate of when an enemy (usually a Notorious Monster) will spawn again.
Avid NM hunters will often note the time of death when another player beats them to the last claim, so they will know when to turn their attention to the area again for their next opportunity. In some circles, particularly among endgame Linkshells, the Time of Death of High Notorious Monsters is a closely guarded secret, as knowing an HNM's Time of Death is the key to claiming it when it next spawns.
It used to be possible to "control" the Time of Death of HNMs (and high-level NMs in general) by keeping them alive after a claim for as long as possible until a desired time was reached, giving players from certain timezones a way to "move" NMs into their time zone. A past update has made this an impossibility with most of the major HNMs, as they will now Rage after a set amount of time.