Mor vs Vita
Modern-day conceptions of Mor and Vita, or the forces of death and life, or immorality and morality, respectively, depicted as the Grim Reaper (left), holding a scythe, and a modern physician (right, holding the staff of Asclepius.
In terminology, Mor, Latin for "dead", root of vis mortua (dead force | potential energy), as contrasted with Vita, root of vis viva (living force | kinetic energy)—i.e. the goddess of life—is the Greco-Roman goddess of death, according to which the “arrival of Mor”, conceptualized in modern times as the arrival of the Grim Reaper, signifies the arrival of death.

In phrase "quieres morir?", in Spanish, to note, translates as "do you want to die?

Terms | Derivatives
The Latin mori means “to die”; which, via Cicero (“On Fate”, 45BC), is the root of the derivative term “moral” and "moral science". [1]

Other Latin-rooted terms include: moribus (customs), mortales (mortals | humans), immortales (immortals | gods). [7]

The famed 10,000-numbered elite troops of Persian empire (550-330BC) were so-named the “immortals”, specifically by Herodotus (c.450BC), because the strength and number was precisely kept at ten-thousand (Ѻ); when a member of the 10,000-strong force was killed or wounded, he was immediately replaced by someone else. This allowed for the infantry to remain cohesive and consistent in numbers, no matter what happened. Thus, from an outsider’s perspective, it would appear that each member of the infantry was ‘immortal’, and their replacement may have represented a resurrection of sorts. (Ѻ)

Common etymologically derivatives of Mor include: moral science, immortality, moral, immoral, mores, moral landscape, moral movement, moral symbols, morality, or morale, e.g. the “morale of the German soldier is not in such a good condition” (Ѻ), from the French feminine of moral (1752), namely: the moral principles, teachings, or conduct; the mental and emotional condition (as of enthusiasm, confidence, or loyalty) of an individual or group with regard to the function or tasks at hand; a sense of common purpose with respect to a group, e.g. “esprit de corps”; the level of individual psychological well-being based on such factors as sense of purpose and confidence in the future. [6]

The Latin phrase Memento mori (remember Mor), “remember death arrives” (Ѻ), the partial philosophical root of the 2000 film Memento, is symbolic of the theory and practice on reflection “mortality”, being representative of the ideological reflective philosophy keeping in mind the transient nature of earthly goods and pursuits.

Mor and Vita
Depictions of the Greco-Roman goddess Vita (left), i.e. "goddess of life", derived from the Egyptian god Ra, i.e. the sun bursting forth from the Nun (pyramid), described by Herodotus as a phoenix; and its parallel Mor (right), the goddess of death, derived from the theory of the death of the sun at nightfall, oft-depicted as pale, gaunt, and floats treacherous and angry like a bird of prey on their victims, until the hour in which she is relentlessly slamming according to the adage “death is certain; though the hour is uncertain” (Mors certa, hora incerta) or "death is certainly, (his) hour uncertain". Mors appears black clad with dark wings and tear the people from his place, as she pleases; reconceptualized as the Grim Reaper in modern folklore.
Egyptian | Religio-mythology
In circa 3,100-300BC, Egyptians, via Heliopolis creation myth turned Anunian theology, invented the conception of bird-like gods and goddess to explain existence and the origin of the cosmos, the origin of "life" or birth of the sun conceptualized as the emergence of bird-god being Ra, called by Herodotus the phoenix, being that something, i.e. a bird, had to carry the sun through the sky each day, in its daily journey. Death, in turn, was conceptualized as the bird-god Ra going below the horizon at nightfall into the underworld.

Here, in turn, the embodiment of death and afterlife was represented by story of the life, death, and resurrection of Osiris, his life-force giver Isis, and their cohort Anubis who weighed the soul in the afterlife.

Greek | Religio-mythology
In the period of the rise of the Greek civilization, and eventual decline of the Egyptian civilization, Greek thinkers began to travel to Egypt to study their cosmology. The Greek pantheon (700BC) was the result, a more anthropomorphized version of the Egyptian pantheon (2000BC), which in turn yielded the Roman pantheon (200BC), out of which, supposedly, Cicero (45BC) coined the term "moral", albeit conceptualized as ethics.

Out of this religio-mythology syncretism transformation, the Greek winged god of death Thanatos, discussed below, resulted; although it remains to be discerned as to which specific Egyptian god[s] or goddess[s] he is modeled on.

In 700BC, Thanatos, the Greek god of death, as described Hesoid’s poem Theogony, was introduced as the son of Nyx (Night) and Erebos (Darkness), twin of Hypnos (Sleep), and sibling to other negative personifications such as: Geras (Old Age), Oizys (Suffering), Moros (Doom), Apate (Deception), Momus (Blame), Eris (Strife), Nemesis (Retribution), and even the Acherousian/Stygian boatman Charon. The following, supposedly, is a synopsis of this logic:

“And there the children of dark Night have their dwellings, Sleep and Death, awful gods. The glowing Sun never looks upon them with his beams, neither as he goes up into heaven, nor as he comes down from heaven. And the former of them roams peacefully over the earth and the sea's broad back and is kindly to men; but the other has a heart of iron, and his spirit within him is pitiless as bronze: whomsoever of men he has once seized he holds fast: and he is hateful even to the deathless gods.”
Hesiod (c.700BC), Theogony (Ѻ)

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Mors (definition)Angel of Death
Left: the standard definition of Mors and Morta according to Michael Jordan (Encyclopedia of Gods, 1993). [5] Right: Carlos Schwabe’s 1895 “La mort du fossoyeur” or the Angel of Death, in which Mor is shown ascending upon the gravedigger: (Ѻ)

Roman mythology
In 200BC, Thanatos was reconceptualized, in Roman mythology terms, into the goddess Mors or Mor. [3]

The various Mor-derivative terms, e.g. “morality”, thereafter, began to derive from the Roman goddess Mors (Latin, female, "Death", genitive mortis), the Roman personification of death, who was associated, albeit distanced from the other three so-called “death gods” of the Roman pantheon: Orcus (carrier of the souls to the underworld), Februus (personification of the “month of the dead”, i.e. February), and Libitian (goddess of funerals), to the effect that her face was seldom portrayed, nor were temples dedicated to her, or were sacrifices offered to her (as they were to Orcus, her male equivalent). [4]

The few details of the personification of death come from poems, in which she is pale, gaunt, and floats treacherous and angry like a bird of prey on their victims, until the hour in which she is relentlessly slamming according to the adage “death is certain; though the hour is uncertain” (Mors certa, hora incerta) or "death is certainly, (his) hour uncertain". Mors appears black clad with dark wings and tear the people from his place, as she pleases.

This would seem to be one of the origins of the later "Grim Reaper" personification of death. The earliest mentions of the Mors can be found in the title of an Fabula Atellana and a satire of Roman writer Quintus Ennius (239-169BC). [3]

American German languages scholar Karl Guthke (1999), argues or outlines the view, supposedly, the term “moral” derives from, or is related, in some way, to the Roman god Mor, the personification of ‘death’ [root of terms such as: rigor mortus, moribund, mortuary science, mortal, etc.], the language equivalent of the Greek god Thanatos, and antithesis, supposedly, to the goddess Vita, the personification of ‘life’ [root of terms such as: vital, vitalism, neo-vitalism, vitality, etc]. [2]

The term “mor”, suggested via the translation of Kim McCone, is the Indo-European word for ‘death”, as in Morrigan, the “queen of death”, the ferrier who brings the soul of the fallen warriors to rest in the Celtic Otherword. (Ѻ)
Freud (Eros and Thanatos) relabeled
Image from 2018 article (Ѻ) on Sigmund Freud’s love drive (Eros), or "life drive", depending on interpretation, and death drive (Thantos) theories.

Freud | Thanatos
In 1930, Sigmund Freud, in his Civilization and its Discontents, employed the Greek gods Eros, god of love, and Thanatos, god of death, as metaphors for his theory of drives:

“The concurrent or mutually opposing action of the two fundamental drives (urtriebe), Eras and Thanatos, explain the phenomena of life.”
— Sigmund Freud (1930), Civilization and its Discontents (pg. #)

A modern illustration of this is shown adjacent, wherein the "angel" with the halo, in its original Egyptian form, is Ra, generally, or Horus or Ra-Horus (aka Ra-Horakhty, "Ra, who is Horus of the Two Horizons"), depending on time period of supreme god syncretism and worship, carrying the sun disk on its head; the “grim reaper”, prior to its Roman god “Mor” embodiment, itself derived from the earlier Greek god “Thanatos” embodiment, had the equivalent of Apep (battling Ra nightly) or Set (battling Osiris [or Horus] annually).

In 1973, Jim Starling, while taking a psychology course, and likely learning about Freud’s death drive (Thanatos) and love drive (Eros) theories, conceived the new comic book character he called “Thanos”, which he recounts as follows:

“I went to college between doing U.S. military service and getting work in comics, and there was a psych class and I came up with Thanos ... and Drax the Destroyer, but I'm not sure how he fit into it, just anger management probably. So I came up to Marvel, and editor Roy Thomas asked if I wanted to do an issue of Iron Man. I felt that this may be my only chance ever to do a character, not having the confidence that my career was going to last anything longer than a few weeks. So they got jammed into it. Thanos was a much thinner character and Roy suggested beefing him up, so he's beefed up quite a bit from his original sketches ... and later on I liked beefing him up so much that he continued to grow in size.”
— Jim Starling (2014), Publication (Ѻ)

In 2019, in the film Avengers: Endgame, which has become the highest growing film ever, the character Thanos, representative of the embodiment of evil, wrong, and darkness, battles the Avengers, representative of the embodiment of good, right, and lightness.

Coupled reactions (Caddyshack diagram)
The Caddyshack social coupling diagram, lecture part 12 (Ѻ), from Libb Thims' 2015 "Zerotheism for Kids" lecture, illustrating coupled reactions in social terms, via the example of nepotism, from the 1980 film Caddyshack.
Morality terminology reform
In terminology reform, morality terminology reform refers to the following upgrades:

MoralExergonic
ImmoralEndergonic

The above were first touched on by Goethe, in his moral symbols (1809) comment, and outlined explicitly and directly by Libb Thims, to children, in terms of why stealing, in general is wrong, during the “Zerotheism for Kids” (2015) lecture.

Quotes
The following are related quotes:

“I have to believe in a world outside my own mind. I have to believe that my actions still have meaning, even if I can't remember them. I have to believe that when my eyes are closed, the world's still there.”
— Christopher Nolan (2000), Memento, ending mental thoughts of the character Leonard Shelby (Ѻ); from the short story “Memento Mori” by Jonathan Nolan—itself based on the Latin phrase Memento mori (remember Mor), “remember death arrives” (Ѻ), which is symbolic of the theory and practice on reflection mortality, i.e. to keep in mind the transient nature of earthly goods and pursuits

References
1. (a) Mor (mythology) – Wikipedia.
(b) Moral – Online Etymology Dictionary.
2. Guthke, Karl S. (1999). The Gender of Death: a Cultural History in Art and Literature (pg. 45-46). Cambridge University Press.
3. Mors (mythology) (German → English) – Wikipedia.
4. Wendell, Leilah. (1996). Encounters with Death: a Compendium of Anthropomorphic Personifications of (Mors, 4+ pgs). Westgate Co.
5. Jordan, Michael. (1993). Encyclopedia of Gods: Over 2,500 Deities of the World (pg. 170). Facts on File, Inc.
6. Morale – Merriam-Webster Collegiate Dictionary, 2000.
7. England, George. (1735). An Enquiry Into Morals of the Ancients (Mor, 2+ pgs). W. Wilkins.

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