The Japanese word “大変” (taihen), made out of the characters for “large” and “change”, and is typically used for two related meanings which I will go over in this post, along with example sentences.
The first is to express something is extreme, and can roughly match with english “very” or “terribly”. When using it as an adverb you don’t need any connecting words (as in the first example sentence below), but when using it as an adjective to modify a noun, you use な like a typical na-adjective.
- I’m terribly sorry.
- Companies are going out of business at a very rapid pace.
It’s important to note that this word used for this meaning is somewhat formal and you wouldn’t likely hear a high school student say “課題は大変難しい” saying in casual conversation, even though it would be grammatically correct.
In this usage there is often a negative meaning implied, which is why I think “terribly” is a close match. Both words have the connotation of something bad or unpleasant, though can be used in a positive sense as well (“I’m terribly happy today!”, though this sounds like British English to me).
The second way is to express a serious, grave, tough, or just generally bad situation.
- Oh no! My car is gone!
- If I don’t finish by today I’m going to be in trouble.
- Bringing up a child is sure tough.
- Today was a rough day, I was running around like crazy since morning.
This usage is a bit less formal and I’ve heard it used much in daily life.