From How your job is killing you by James Adonis in the Sydney Morning Herald (I try to avoid giving free publicity to companies, but I’ve got to credit my sources):
The Japanese have a word, karōshi, to describe people who work themselves to death. … In China the word used is guolaosi. … South Korea, too, has a term for this pervasive condition: gwarosa.
A little bit of linguistic knowledge shows that those are actually the same word, in the pronunciation systems of those three languages. Japanese and Korean have borrowed a large number of words directly from Chinese, and have also created new words themselves from Chinese characters.
Because hangeul is such an elegant spelling system, I was able to figure 과로사. Google Translate reports that this means overwork, which by itself is not a fatal condition. 과로 by itself is strain and 사 four, which isn’t relevant (or is it?). Searching the internet for guolaosi, I found a Chinese English Pinyin dictionary, which reports that it is trad. 過勞死 simp. 过劳死 guò láo sǐ karoshi (loan word from Japanese), death from overwork. So it seems that this word was coined in Japan from Chinese character words, then borrowed into Chinese and Korean. Searching for karoshi, I found the Urban Dictionary’s entry for karosi, which reports (with due caution about relying on the Urban Dictionary):
Death caused by too much hard over-working. This term is from Japanese. Korean and Japanese has this word that can be written in chinese character. Karosi is consisted of 3 chinese character which means over, work and death.
Let’s look at that Korean word 사 again. Many lifts in Korea have buttons marked 1, 2, 3, F, 5 … The explanation is that the Korean word 사 sounds like the Chinese word for death, which just doesn’t make sense to me. An equivalent would be avoiding the word English word forty because it sounds like the French word mort. Marking the lift button F doesn’t stop the fourth floor being the fourth floor, especially if you call the next one ‘5’. It doesn’t even stop the fourth floor being the fourth floor even if you call it ‘5’. My wife said some people might avoid buying an apartment on the fourth floor, but those who do live or work on the fourth floor have no difficulty in saying, ‘My apartment is on the fourth floor’ or ‘I live in apartment 401’. Also, ‘four’ is widely used in bus routes and telephone numbers.
My wife also said ‘But don’t people in English speaking countries avoid 13?’. Some people, maybe, but seeing lift buttons with 12A or no 13 at all is very rare compared to seeing Korean lift buttons with F.
When I returned from Korea last year, I needed a new mobile telephone number. The salesperson said ‘Does a number with a lot of 4s bother you?’. I said ‘No, why should it?’. He said ‘A lot of Chinese people specifically ask for a number with no 4s’. So, my mobile telephone number has a lot of 4s. If I die in the next 50 years, you’ll know why.