Eternal being is something that springs to mind as a
divine characteristic. In modern
monotheism, "dead god" seems like an
oxymoron. We have to turn to
pagan myths, such as
Greek and Roman Mythology, to find "dead gods".
There is no "definitive version" of
Greco-Roman mythology to draw on; the best sources are sketchy on the details of the eventual
fate of
deposed gods
Uranus and
Kronos. I contend that they became "dead gods": their worship was so inappropriate as to need no forbidding. These were
Big Loser gods; no one would want them for patrons. Regardess of whether they are supposed to be hanging around in exile in
Tarterus, or completely dead, they have no impact on the lives of the people who believe they did, or do, exist.
This is what it means, to
mortals, for a god to be "dead": removed eternally from
intervention in
mortal affairs, or even the affairs of other gods.
In
Gloranthan mythology and
metaphysics, pretty much anything can be permanently destroyed if it is lost in the
Void that is
Primal Chaos. This includes gods: when
The Unholy Trio cracked the Universe and let
Chaos in,
Ragnaglar was overcome by Chaos, and became Glorantha's first Dead God. The illusion of
death, such as
Yelm's murder and subsequent rescue from
Hell, does not compare. A
Quest may restore what has succumbed to the mere sting of Death, but no power can recall what is consumed by Chaos.