Holiday
National Holiday, Public Holiday
noun, の adjective
A festival day literally means "festival day," as in a day for Shinto festivals or rituals. These days, though, it really just means holiday.
Usually this will be a national holiday or public holiday, since some Japanese public holidays are based on Shinto festival days. 祭日 was the official term for public holidays prior to World War II, but today 祝日 is used in its place. Because of this, it sounds a little old-fashioned now, but you may still encounter it occasionally.
This is a jukugo word, which usually means on'yomi readings from the kanji. Since 日 has two on'yomi readings, here's a mnemonic to help you remember which one to use:
Apparently there are two holidays this week. Gee, two (じつ)? Lucky you. You should probably think of some fun stuff to do over these two holidays.
今日は祭日だからいつものカフェがお休みだったよ。
Today is a national holiday, so the coffee shop I usually go to was closed.
祭日なのに、仕事なの？
You have to work even though it's a national holiday?
祭日だってことを忘れていて、会社に来てしまった。
I'd forgotten it was a holiday, so I ended up coming in to the office.