大変
たいへん
taihen
= tough; hard; serious; terrible; (as adverb) very; extremely
大変 is one of those words that does a lot of work in Japanese — it tells you that something is genuinely difficult or serious, and as an adverb it quietly cranks the intensity of whatever comes after it.
大変 (taihen) has two main uses that learners must keep distinct. As a na-adjective it means “hard,” “tough,” or “terrible” — describing situations that are a struggle or a big deal (大変な仕事, taihen na shigoto, “a tough job”). As an adverb it means “very” or “extremely” and modifies adjectives or verbs (大変お世話になりました, taihen osewa ni narimashita, “thank you very much for your help”). The adverbial use is especially common in polite or formal registers; in casual speech, とても (totemo) or すごく (sugoku) are more frequent alternatives. The na-adjective use, however, is flexible across all registers and conveys genuine weight — saying 大変だ! is a natural exclamation when something has gone wrong.
When 大変 is used as an adverb in formal settings (e.g., 大変ありがとうございます), it sounds more refined than とても. Avoid swapping them freely in business emails — とても ありがとうございます exists but sounds slightly less formal. Also watch out for context: if someone says 大変だ! they are not saying “it’s very” — they mean something is serious or wrong, so read the surrounding situation carefully.
大 (dai/oo) means “large” or “great.” 変 (hen/ka) means “change” or “strange,” and in compounds it carries a sense of abnormality or upheaval. Together 大変 originally meant “a great upheaval” — its modern sense of “serious trouble” or “very” evolved from that core idea of something being out of the ordinary in a significant way.
Everyday use
引っ越しは大変だったけど、なんとか終わったよ。
Hikkoshi wa taihen datta kedo, nantoka owatta yo.
Moving was tough, but I managed to get through it.
Formal / Cultural context
大変お待たせいたしました。
Taihen omatase itashimashita.
I am very sorry to have kept you waiting.
Casual / Social Media
え、財布なくした？それは大変！
E, saifu nakushita? Sore wa taihen!
What, you lost your wallet? That’s terrible!
大変 as an adverb is a staple of Japanese business communication. Phrases like 大変お世話になりました (thank you greatly for your support) and 大変申し訳ございません (I am deeply sorry) appear in emails and customer service interactions because 大変 elevates the sincerity of the expression beyond what とても conveys in formal contexts.
The exclamatory use of 大変だ! in casual speech reflects a cultural tendency to understate until something genuinely rises to the level of 大変. Japanese speakers reserve the word for moments that actually feel serious — using it for minor inconveniences can come across as dramatic. Learners who use 大変 for small problems may sound like they are overreacting.