Does Korean have native words corresponding to 형 and 동생?

Question

Korean sibling terms are quite interesting but also a little odd. While terms like eonni, nuna and oppa seem to be native, hyeong and and dongsaeng are Sino-Korean. What would be the reason for this? Were there once native terms that were supplanted somehow? Compare similar Old Japanese native kinship terms which mostly managed to survive into modern Japanese: imouto "male's sister", now "younger sister"; ane "elder sister"; shouto "female's brother", now archaic; ani "elder brother"; otouto "younger sibling", now "younger brother".

Answer 1

The other two answers provide partial insight, but not the whole story. Let me combine those two and provide some more background.

언니 was indeed used to refer to a male's older brother as well, as @jick says, but this word only starts to appear in records in the late 19th century. There is no evidence that this word was used before that time.

Then, what was used instead? The answer is: "형". "형" is now only used to refer to a male's older brother, but in the past, it was used to refer to a female's older sister as well.

Basically, "형" used to mean "one's older sibling who has the same gender". This usage is fossilized in the term "형님", which is also used by females to address their older sister-in-law.

Here's an instance of "형" being used in Middle Korean that is used to refer to a female's older sister, in <석보상절 권6> from 1447:

아ᄌᆞ〮마니ᄆᆞᆫ〮 大땡〮愛ᅙᆡᆼ〮道또ᇢ〯ᄅᆞᆯ 니르시〮니〮 大땡〮愛ᅙᆡᆼ〮道또ᇢ〯ㅣ 摩망耶양夫붕人ᅀᅵᆫㅅ 兄ᄒᆑᇰ니〯미〮시니〮 야ᇰᄌᆡ〮 摩망耶양夫붕人ᅀᅵᆫ만〮 몯〯ᄒᆞ〮실ᄊᆡ〮 버근〯 夫붕人ᅀᅵᆫ이〮 ᄃᆞ외시〮니라〮

Translated word-for-word to Modern Korean, the above would be:

"아주머님"은 대애도(大愛道)를 이르는데, 대애도가 마야부인의 형님이시니, 인물이 마야부인만 못하신 까닭에 둘째 부인이 되셨다. 〈석보상절06:1a-1b〉

In English:

The "aunt" refers to Pajapati. Pajapati is Queen Maya's older sister. Her appearance was not as beautiful as Queen Maya, so she become the second wife.

Then, where does the word "언니" come from, if it just suddenly appeared in the 19th century? There are a lot of theories, but the most convincing one is that it is a corruption of the word "형님" from "형(兄)" (same-sex older sibling) + "-님" (honorific). There are several evidences that support this theory, but I won't go into that here.

In Middle Korean, the system of kinship terms for siblings were quite different from how they are now. As I said before, 형(兄) was used for "same-sex older sibling", but what about others? I summarize those in the table below:

		male's	female's
older	brother	형	오라비
	sister	누의	형
younger	brother	아ᅀᆞ	오라비
	sister	누의	아ᅀᆞ

In short, there were four "basic" sibling kinship terms in Middle Korean:

• "형": "same-sex older sibling"
• "아ᅀᆞ": "same-sex younger sibling"
• "오라비": "female's (older/younger) brother"
• "누의": "male's (older/younger) sister"

Out of those four, only one, "형(兄)" is Sino-Korean. Why is this so? I don't know. What was used to refer to "same-sex older sibling" before 兄 was loaned into Korean? I don't know, but some people suggest that "맏이" (which now means "firstborn" or "eldest sibling") originally referred to "same-sex older sibling", although there is no evidence.

When did 동생(同生) "younger sibling" begin to be used? 동생 (도ᇰᄉᆡᇰ in Middle Korean) did exist in Middle Korean, but it originally used to mean "siblings coming from the same parents" (as opposed to siblings-in-law). This is evident from the Hanja: 동(同) "same" + 생(生) "born".

Through a semantic shift process, 동생 now means "younger sibling", and these supplanted the earlier "아ᅀᆞ", "누의", and "오라비". (But "누의" and "오라비" kept living on restricted to "older" siblings, becoming "누의 + 님 > 누님 + 아 > 누나" (male's older sister) and "오라비 + -아 > 오빠" (female's older brother))

Answer 2

Yes, the native word for 형 is... (drum roll please...) 언니.

It used to be gender-neutral, but now it's pretty much restricted to female-female relation.

According to Naver dictionary for 언니:

같은 부모에게서 태어난 사이이거나 일가친척 가운데 항렬이 같은 동성의 손위 형제를 이르거나 부르는 말. 주로 여자 형제 사이에 많이 쓴다.

The native term for 동생 is 아우 - I think it's considered old-fashioned these days, but it's still used in stock phrases such as 형만한 아우 없다.

Answer 3

In Middle Korean texts, 오누이 (with Middle Korean tone marks and spelling: 오〮누의〮) was equivalent to 'siblings' (now supplanted by the hanja-eo 남매).

This is equivalent to unattested *올 'brother' + a well-attested lexeme '餒必' in early Middle Korean and in later Middle Korean as 누의 'sister'.

The former survives in reflexes like 오라비 (< *올 + 아비 'father/man', Middle Korean 오〮라비〮) and, with the vocative -아 suffix, the modern 오빠.

The latter survives as 누이, in Gyeongsang-do as 누부 and in Yukjin as 누비/누배; in a similar process with the vocative -아 suffix and possibly the honorific 님, as 누나.

Did *올 and 누의 ever refer to younger siblings? We do have 아ᅀᆞ in Middle Korean, now 아우 in the standard, for a man's younger brother. But what about a man's younger sister, or any of a woman's younger siblings? It seems the *올 and 누의 reflexes were used in such cases. See here for a previous answer.