What is an ORC?
The name orc comes from various reallife folkbeliefs.
Ultimately the term comes from Roman folkbelief, Latin orcus, the name of the underworld (and of its Roman god).
Etymologists explain orcus derives from a Proto-Indoeuro term meaning to "lock up", "shut away", "guard". The English term arcane also derives from this in the sense of "kept secret". Some etymologists note a possible connotation from the Greek term horkos, meaning an "oath" from the sense of "locking in" a promise. Generally, orcus means the dead are locked away in the grave.
The term orc finds its way into Old English (West Saxon dialect), specifically in Beowulf. The date seems disputed, somewhere 700s thru 900s. The term is a compound noun, orcné, meaning a "corpse" né of the "underworld" orc. In other words, an orc is an undead.
Elsewhere in Old French, this earlier term orc came to be pronounced as ogre (by metathesis). Ogre is attested since the 1200s to mean a "human-eating giant", or in an other context, a "fierce Nonchristian". In the sense of "giant" there might be a sense of one who comes to punish the breaker of an "oath".
Relatedly, Old Spanish transmits a cognate of Latin orcus, namely huerco, meaning the "devil" in Christianity. In this process of demonizing pagan folkbeliefs, the underworld in the sense of the realm of dead came instead to be understood as the hellish lake of fire, whence its god equates to the satan. (Probably this likewise relates to the Old French ogre in the sense of a "Nonchristian".)
Like the Old French ogre, Italian uses its term orco to mean a "giant".
With all of this mind, Tolkien himself an etymologist reused the Old English term orc to mean the Christian "hell", thus in the sense of a corpse of hell, reused the term orc-né to mean the corpse of a demon. Whence the Tolkien orc is a "demon", which in his fantasy world is equivalent to a "goblin". The creation of the Tolkien orc is a modified "elf", becoming "savage" and corrupted by evil.
Translating all of the folkbeliefs into D&D opens up many interesting flavors.
In every edition of D&D, the D&D Orc has never felt like a Tolkien orc. The Orc has never been a demonic elf. It was more a mix of human and animal. Early editions did feel like Orc and Goblin were interchangeable, at least in usage, but that has been untrue since 3e. The Orc was always tall about 6 feet, but by 5e the giantlike qualities of the Orc are more evident. And the Fey small sprite qualities of the Goblin are more evident.
Given the reallife meaning, Orc = Ogre, I want to emphasize the D&D Orc is the D&D Giant creature type. Specifically, the Orc is a kind of Ogre that is more humanlike, hence the Humanoid creature type. I would like D&D 2024 to say phrases like, the Orc is a "Humanoid Giant".
Where the Orc is a creature of underworld, namely the D&D Shadowfell, is fascinating. In Beowulf, the "underworld corpse" seems to be an Undead creature type. However, in other contexts of "orc" such as "ogre", this is more like: the Orc is the forces of death that come from the Shadowfell.
Orc can come with necromancy flavors. There different kinds of Giants, perhapse the Ogre and Orc are more like "Death Giants".
At the same, the connotation of underworld might merely refer to a being from the ground itself. In other words, these giants are nature beings of mountains and hills, etcetera. This suggests some Elemental aspects.
The Orc also comes with the meanings of a D&D Fiend via the Christian hell and devil. I feel the Astral creature Gruumsh can have all of these fiendish connotations, and the Orc itself, none of it.
Note also, the D&D necromantic Fiend Orcus can share some of its necromantic flavor with the Orc.
Now, I definitely want to say, the Orc is a kind of Giant. A necromantic one seems interesting.
When what defines an Orc is so fantastical and so inhuman, it is easier to describe the Orc in a distinctive flavorful way, without referencing any reallife human ethnicities.
In D&D history, the descriptions of the Orc were actually racist (representing tropes from East Asian "yellow" orcs with "shamans", Indigenous American "red" orcs, and Black African "withdoctors" of dark skinned "savage tribes", who must be conquered).
It seems easy to delete all of this reallife racism. Focus on the unique kind of Giant flavor instead.
