A day when one does not work or attend school; can refer to public holidays, company holidays, or personal days off.
Today is a holiday, so the office is closed.
次の休日は何をしますか。
What will you do on your next day off?
Since this week was busy, I decided to take a day off.
I spent a quiet day off with my family.
I like going to see movies on my days off.
休日 is a general word for any day off or holiday, whereas 定休日 specifically means a business's regularly scheduled closing day.
the day after a holiday
substitute national holiday; compensatory public holiday · compensatory day off; lieu day