平日（へいじつ、heijitsu）
- weekday

The Japanese word 平日 (へいじつ - heijitsu) primarily means "weekday" or "workday." It refers to the days of the week that are not Saturday, Sunday, or national holidays when most people are expected to be working or attending school. It implies a time when businesses and institutions are typically open and operating. It's important to note the concept of 平日 excludes weekends and national holidays.

⚫︎ 平日はいつもより電車が混んでいます。 Translation: The trains are more crowded on weekdays than usual. ⚫︎ あの店は平日は午前10時から営業しています。 Translation: That store is open from 10 am on weekdays. ⚫︎ 平日のランチは安いです。 Translation: Lunch is cheaper on weekdays.

You use 平日 in situations where you want to specify a day that is not a weekend or a holiday. It is commonly used when discussing business hours, train schedules, or activities that are typically done during the work week. You can use it when comparing things during the week versus the weekend or a holiday. You can also use it to contrast regular schedules and availability with those that are altered for holidays or weekends.

平日 is typically written with the kanji 平日. The reading in hiragana is へいじつ. There are no other common ways to write this word. The okurigana is standard.

There aren't many perfect synonyms in Japanese, but words like 営業日 (えいぎょうび - eigyōbi), meaning "business day," or 勤務日 (きんむび - kinmubi), meaning "working day," can sometimes be used in a similar context, but often with more specific meanings.

The direct antonym of 平日 is 休日 (きゅうじつ - kyūjitsu), which means "holiday" or "day off." Other antonyms are 週末 (しゅうまつ - shūmatsu) meaning "weekend."

平日の朝は、早く起きなければなりません。 ・Translation: I have to get up early on weekday mornings. ・Explanation: This sentence uses 平日 to indicate the mornings when one must go to work or school, contrasting them with the more relaxed weekend mornings.

平日に映画を見に行くのは、人が少なくていいですね。 ・Translation: It's nice to go see a movie on a weekday because there are fewer people. ・Explanation: This sentence compares the experience of going to the movies on 平日 versus the often-crowded weekend times.

The word 平日 is a combination of two kanji: 平 (hei), meaning "level," "even," or "ordinary," and 日 (nichi/bi), meaning "day." Therefore, 平日 literally translates to "ordinary day" or "common day" and this reflects its meaning as a regular working day.