In response to a question about the differences between these verbs, user “Tony” on italki gave an answer that I liked:
– 떨어지다: fall, drop from a height. 걸어 둔 액자가 떨어졌다 (A picture frame on the wall fell down).
– 무너지다: crumble, fall apart. 큰 건물이 무너져 버렸다 (A big building crumbled down).
– 쓰러지다: fall over; fall onto one’s/its side. 심한 현기증에 쓰러졌다 (Fell down from an acute dizziness).
– 넘어지다: fall by slipping or tripping. 너무 서두르다가 넘어졌다 (Fell while trying to go too fast).
I was comfortable with 떨어지다 but I pressed him further on the differences between 무너지다 and 쓰러지다, and he said this:
“쓰러지다 sounds like something tilts and falls over to the ground (and it may still be in one piece after it collapses), while 무너지다 implies something massive gives way and falls straight down (and disintegrates structurally). So we sometimes say 쓰러지다 if a narrow, tall building collapses but 무너지다 for any massive structure.
Since people and animals (and plants too) stand tall on their skinny legs, and because the change is just in the stance and posture, we say 쓰러지다 and never 무너지다.
Interestingly, 무너지다 is sometimes used to describe a mental state like an expectation or confidence, as in 나의 기대는 여지없이 무너졌다. This is probably because 무너지다 emphasizes a complete crumbling so that recovery is nearly impossible.”
After Tony’s explanation, I was pretty satisfied with the the difference between 무너지다 and 쓰러지다. However, 쓰러지다 and 넘어지다 still gave me trouble. They seemed to be the most similar of the four verbs.
The 한국어-영어 학습사전 says 쓰러지다 means “For something standing to fall sideways.” / 서 있던 것이 한쪽으로 쏠리어 넘어지다. (쏠리다 means “to lean”.)
넘어지다 is defined in the same dictionary as “For a standing person or object to lose balance and fall down.” / 서 있던 사람이나 물체가 중심을 잃고 한쪽으로 기울어지며 쓰러지다.
Comparing the Korean definitions, 쓰러지다 and 넘어지다 are defined in terms of each other! So I could just say they’re synonyms and leave it at that. But I wanted to do better.
I thought looking at a bunch of examples could help. First, some examples for 쓰러지다 from Naver:
상자들이 쓰러지다. (상자들 = boxes)
태풍 때문에 집 앞에 있는 나무가 길에 쓰러졌다.
그 건물은 너무 오래 되어서 쓰러질 지경이었다.
가: 저 위에 쌓은 상자들 쓰러지기 전에 정돈하여라.
나: 네, 사다리 좀 주세요.
User “supra” on hinative offered an interesting explanation for the difference between the two verbs:
“쓰러지다 it means falling down by itself because if loose mind or tired or shocked or hitting. but 넘어지다 means falling down by something or someone accidentally.
할머니가 넘어지셨어 (돌에 걸려서)
배가 고파서 쓰러지겠어
배가 고파서 넘어지겠어 X
아이가 조심성이 없어서 자주 쓰러져요X
아이가 조심성이 없어서 자주 넘어져요.”
But I ran into conflicting information. My Casio dictionary from the 90’s (which my wife used while learning English) has an example sentence “나는 돌에 걸려 쓰러졌다.” Wouldn’t 넘어졌다 be a more natural fit?
Another vote for supra’s answer came from user Freshmango.
TTMIK, a popular source for Korean learning, tweeted this:
“떨어지다 = to fall (down from high up), to drop
무너지다 = to collapse (ex: building, reputation, sand castle, etc.)
넘어지다 = to fall over (from standing or walking)
쓰러지다 = to fall down (ex: tree), to have a breakdown”
Comparing TTMIK’s and Tony’s definitions, there’s still some ambiguity with 넘어지다 and 쓰러지다. In the Naver Basic dictionary, sentence structures are given to show verbs’ typical usage, and the sentence structures for these two verbs are slightly different. 넘어지다 can be used in the form 1이 2에/로 넘어지다, whereas 쓰러지다 is limited to 1이 2에 쓰러지다. So what’s the significance of the 로?
I returned to my Casio dictionary and found what I believe to be the key example for these two verbs:
바람으로 나무가 쓰러졌다. / The wind brought [blew] down the trees.
바람에 나무가 넘어졌다. / The wind brought [blew] down the trees.
The first Korean sentence from my Casio contradicts the sentence structure in Naver’s Basic dictionary, adding to my confusion.
But the question is this: If a tree falls in the woods, does it 쓰러져 or 넘어져?
I found a video of a tree falling in a storm. It’s labeled “쓰러지는 나무”.
Then I discovered another person had posted the identical video with the label “나무 넘어지는 영상”! Another vote for the synonym theory.
I came across another interesting explanation from 한국어 교실 blog. The key example is this:
아이가 조심성이 없어서 자주 넘어져요. (okay!)
아이가 조심성이 없어서 자주 쓰러져요. (sad buzzer sound)
The reason that sentence #2 doesn’t work, according to 한국어 교실, is that 쓰러지다 implies that the person’s energy or life force is used up, causing them to fall. Clearly a kid has no problem with lacking energy, so the kid must be 넘어지-ing due to external influences (pardon the Konglish).
So it seems to me that while 쓰러지다 and 넘어지다 are interchangeable when describing a falling tree, they’re pretty distinct in most cases. And I speculate that even the falling tree could be understood differently depending on which verb is used. In light of the above analysis, a 쓰러지는 나무 gives me the feeling of a weak or dying tree, collapsing in the wind because its life force is exhausted. Whereas a 넘어지는 나무 gives me the feeling of a healthy tree getting battered by the wind until its trunk snaps.