お湯: when “hot water” isn’t water

I’ve written before about how it’s hard to grasp a word’s true meaning and usages just by looking it’s dictionary entry. There are often subtle nuances or assumptions missing. This time I’d like to talk about one such case.

湯 (“yu”, sometimes written as お湯, “oyu”) is a word which means “hot water”. I had learned this some time back, and thought this concept was pretty straightforward. If I heard the word 湯 I’ll know it means hot water – simple.

However one day when I was trying to describe some water which happened to be hot, I used the word “水” (mizu) which as you probably know means plain “water”. Of course I could have called it 湯 but hot water is water after all, right?

Not quite. Though I think hot water could technically be classified as ”水”, in everyday conversation this word would be used to refer to non-hot water. So if the water was really hot, I was told I should use 湯. If I was writing a dictionary I would probably indicate 水 usually refers to non-hot water as to avoid confusion from day one.

Similarly, though the phrase “熱い水” (literally “hot water”) is not technically incorrect, it is much more natural to say 湯. It would be natural to say “暖かい水” (“warm water”), however.

The word 湯 also has an extended meaning of bath water, because that is typically hot. This can be the water inside of a bathtub at home, or in a traditional bathhouse. The dictionary says 湯 can refer to the bathhouse as a unit, and although I’ve never heard this I have seen the symbol ゆ (yu) on the bathhouse in the classic anime film Spirited Away.

Differentiating between the polite prefixed versions of words (お湯、お名前) and the normal versions (湯、名前) is usually pretty tricky in Japanese, though in the case of お湯 I’ve been told that it has a sense of pure or clean water that you would drink (probably water that has been boiled).

So if I take some 水 and I boil it, does it magically turn into お湯? Yes, it does, and there is an expression お湯を沸かす which means to boil water.