It's awfully hot today, isn't it?
Thank you very much for your help.
Used when something requires great effort or is physically/mentally demanding; often in the pattern ～は大変だ.
Cooking every day is hard work.
Raising children is tough but enjoyable.
Archaic noun meaning a calamity or great event; rarely used in modern Japanese outside historical or literary contexts.
In old documents, 大変 is sometimes used to mean a disaster.
This book is very interesting.
I heard there was a terrible accident at the station.
Taking care of small children is hard work.
Your help was a huge relief to me.
大変 works fine in casual conversation, whereas 甚だ is literary and rarely heard in everyday chat.
大変 is a broad, everyday word for something difficult or a lot of work, while 苦しい is heavier and implies real pain, pressure, or hardship.
大変 is a common intensifier usable with both adjectives and verbs in polite speech, while 大いに leans toward emphasizing the degree of an action.
大変 objectively describes a difficult or serious situation, while 辛い expresses the subjective feeling of hardship.
大変 is a very common, everyday intensifier, while すこぶる is rarer and belongs to more written or formal registers.
大変 is a polite, widely used intensifier for 'very', whereas 随分 leans toward expressing the speaker's surprise at an unexpected degree.
大変 is a softer, widely-used intensifier suitable for casual and polite speech, whereas 極めて is more formal and used mainly in writing or formal speech.
大変 is a more formal intensifier suitable for polite or written contexts, whereas 凄い/すごく is casual and used mainly in spoken Japanese.
大変 is the common word for something being tough or serious, while 偉い in casual speech carries the same 'tiring/terrible' sense but sounds more colloquial or dialectal.