二倍（にばい、nibai）
- double

The Japanese word 二倍, pronounced にばい (nibai), means "twice" or "double." It signifies a quantity or amount that is multiplied by two. It is a fundamental concept used in mathematics and everyday conversations to express an increase or a doubling of something. This word indicates that something is 二倍 the size, amount, or value of another thing.

⚫︎ このケーキはいつもの二倍の大きさです。 Translation: This cake is twice the size of the usual one. ⚫︎ 今日の売り上げは先週の二倍でした。 Translation: Today's sales were double those of last week. ⚫︎ 彼女は彼の二倍早く走れる。 Translation: She can run twice as fast as him.

二倍 is used in various situations where you want to express that something is doubled. ⚫︎It can be used in business settings, such as discussing sales or profits. ⚫︎It's common in mathematics to talk about multiplication. ⚫︎It's also utilized in casual conversations when comparing quantities or sizes. The word is versatile and can apply to both concrete and abstract concepts. It directly expresses the idea of a 二倍 increase.

二倍 is typically written in kanji and hiragana: 二倍. ⚫︎ 二 (ni) represents "two". ⚫︎ 倍 (bai) means "times" or "fold". The reading is にばい. There are no other ways to write this word, and the okurigana is fixed.

⚫︎ 二つ分 (futatsu bun): Meaning "two portions" or "two times the amount". ⚫︎ 倍加 (baika): This is a more formal way of saying "doubling" or "multiplying by two".

⚫︎ 半分 (hanbun): "Half" ⚫︎ 半額 (hangaku): "Half price"

彼は二倍の時間をかけて宿題をしました。 ・Translation: He spent twice the amount of time doing his homework. ・Explanation: This sentence uses 二倍 to indicate the amount of time spent on homework was doubled.

この薬は一日に二倍の量を飲んではいけません。 ・Translation: You must not take twice the amount of this medicine in a day. ・Explanation: This sentence warns against taking twice the prescribed amount of medicine.

The word 二倍 is composed of two kanji: 二 (ni) meaning "two" and 倍 (bai) which means "times" or "fold." The combination of these two characters explicitly conveys the concept of doubling or multiplying by two.