Yaarel
🇮🇱 🇺🇦 He-Mage
Heh, Gygax makes knowledgeable people cry.D&D and etymology don't really mix that well.
We could actually have a pretty good thread about how screwed up D&D's idea of monsters is from a folkloric perspective. Basilisks and cockatrice are different creatures somehow. As are gorgons, medusae and catobelopas.
And then on this very topic:
Hobs, redcaps, brownies, faries, fairys, sprites, pixies, elves, dwarves, sidhe, and goblins? All the same guys.
Gnomes, kobolds, and earth elementals (as said). Different set of same guys.
Trolls? A class onto themselves, rather like saying 'bird' or mammal for all the the variety you're lumping together.
Orc? Basically a modern invention that's actually newer the 'robot' as its own thing.
I'm honestly shocked D&D back in the 80's didn't somehow have singular monsters called youkai, tengu, garuda and rakash...ah crap...
Hobs are house spirits.
I associate Redcap with the red cap of Nisse (a Scandinavian house sprite). But "redcap" actually is a demonic sprite in Scottish lore that really did keep it red by dipping it in blood.
Fairy. The word "fairie" (of many different spellings) means "magic", as well as "realm of fay". In British lore, the term fairy meant any kind of magical creature, including a sphynx. However, as the term came more and more to specify the fairy as described by Shakespeare, new terms entered the language to fill in the gap (like "magic" as a neologism to replace "fairy"), and to help disambiguate (like using "elf" to mean a human size fairy).
A goblin (ultimately from German kobold via French), is in English synonymous with boggard, and so on, and is a malevolent sprite, as opposed to a hob which is a helpful sprite. The term "hobgoblin" is an oxymoron where a sprite that plays practical jokes that cause pain and laughter, is both helpful and harmful, simultaneously. In this sense, Shakespeare uses hobgoblin for Puck (≈ bug, bogey, boggard, puk, boogie, etcetera), as the royal jester of the fairy court.
Sidhe are a Celtic land spirit. In Scotland Sith is an other name for an Elf in the sense of a human size fairy.
For me Dwarf in the sense of Norse Dvergar is a highly specific concept.
The Norse word "troll" means "enchanter", "witch". Under Christian influence, it came to be a Scandinavian loantranslation for the British term "fairy", which in the sense fate and magic, also means "enchant". Trolls are various magical creatures, and in Scandinavia there are very different kinds of trolls from beautiful to grotesque, but they came to be understood as members of the same family.
Orc is apparently a word occurring once in Old English, in Beowulf, as orcneas, of unclear meaning but in a context of various magical creatures.
Any way, in D&D, Halfling and Gnome resemble each other and often get grouped together. That their etymology says they are both a kind of house sprite is telling.
Even the 5e art for a Halfling looks much like pop-culture images of a Gnome.
(Heh, one could almost argue that a Halfling is a Half-Gnome, descending from Human and Gnome parentage. Heh, these hybrids remain Small but become less magical.)