分子（ぶんし、bunshi）
- molecule

The Japanese word 分子 (ぶんし) has multiple meanings, primarily related to mathematics and science. ⚫︎ In mathematics, 分子 (ぶんし) refers to the numerator of a fraction. This is the number above the line in a fraction. ⚫︎ In chemistry, 分子 (ぶんし) means "molecule." A molecule is the smallest particle of a substance that can exist independently and still retain the chemical properties of that substance. It's formed when two or more atoms bond together.

⚫︎ 分数（ぶんすう）の分子は3です。 Translation: The numerator of the fraction is 3. ⚫︎ 水は水素と酸素の分子からできています。 Translation: Water is made up of molecules of hydrogen and oxygen. ⚫︎ この物質は複雑な分子構造を持っています。 Translation: This substance has a complex molecular structure.

The word 分子 (ぶんし) is used in specific contexts. ⚫︎ When discussing fractions, use it to refer to the numerator. ⚫︎ In chemistry and related fields, it refers to molecules. ⚫︎ It's generally not used in everyday casual conversation unless you're discussing science or math topics.

分子 (ぶんし) is typically written using: ⚫︎ Kanji: 分子 ⚫︎ Hiragana: ぶんし (used for pronunciation) ⚫︎ There are no significant variations in writing or okurigana.

There aren't many direct synonyms in Japanese for the two primary meanings: ⚫︎ For the numerator of a fraction, there isn't a direct synonym as it's a specific term. ⚫︎ For "molecule," the closest synonym might be 分子構造（ぶんしこうぞう） (molecular structure), although it is a more descriptive term rather than a direct synonym.

⚫︎ For the numerator in a fraction, the antonym is the denominator. The word for denominator in Japanese is 分母（ぶんぼ）. ⚫︎ There isn't a direct antonym for molecule. It is a fundamental concept in chemistry. However, "atom" could be considered an antonym in the sense that atoms combine to form molecules. The Japanese word for "atom" is 原子（げんし）.

この化学反応では、新しい分子が生成されます。 ・Translation: In this chemical reaction, new molecules are created. ・Explanation: This sentence uses 分子 in its chemical meaning, talking about the creation of molecules.

分数（ぶんすう）の分子と分母を足してください。 ・Translation: Please add the numerator and denominator of the fraction. ・Explanation: This sentence uses 分子 in its mathematical meaning, referring to the numerator of a fraction and using the word 分母 (denominator) as its pair.

The word 分子 (ぶんし) is composed of two kanji: ⚫︎ 分 (分): This kanji means "part," "segment," or "minute." ⚫︎ 子 (子): This kanji means "child" or "seed." ⚫︎ Thus, the literal meaning could be understood as "parts of something" or "a small portion" which aligns with its use in both mathematics (parts of a whole) and science (the smallest unit of a substance). ⚫︎ The etymology reflects how it came to be used in both science and mathematics, by referring to something small or a part.