In school maths, a binomial is an expression made of two parts joined by plus or minus. 3x + 4y is a binomial. So is x − 7. Even 5 + 2 counts, because it still has two terms.

In school maths在學校數學裡，a binomial二項式 is an expression made of two parts是由兩個部分組成的式子 joined by plus or minus用加號或減號連接起來。3x + 4y is a binomial3x + 4y 就是一個二項式。So is x − 7x − 7 也是。Even 5 + 2 counts就連 5 + 2 也算，because it still has two terms因為它一樣有兩項。

One piece by itself, like 3x, is a monomial. Three pieces, like x² + 2x + 1, is a trinomial. Polynomial is the family name for these 'many-term' expressions; a binomial is the two-term kind.

One piece by itself單獨一項，like 3x像 3x 這樣，is a monomial叫做單項式。Three pieces三項，like x² + 2x + 1像 x² + 2x + 1 這樣，is a trinomial叫做三項式。Polynomial「多項式」 is the family name for these 'many-term' expressions是這種「很多項」式子的總稱；a binomial is the two-term kind二項式就是剛好兩項的那種。

You meet binomials when you multiply them, and in the binomial theorem, a pattern for raising a two-part expression to a power, like (x + 1)⁵. The word belongs in the classroom and the textbook, not on the bus.

You你 meet binomials會遇到二項式 when you multiply them在相乘的時候，and in the binomial theorem也會在「二項式定理」裡遇到——a pattern for raising a two-part expression to a power那是把一個兩項的式子取次方的規律，like (x + 1)⁵像 (x + 1)⁵ 這樣。The word這個詞 belongs in the classroom and the textbook是屬於教室和課本的，not on the bus不會出現在日常閒聊裡。

Though actually, the same word walks into biology. Scientists name living things with two names, a group name and a species name: Homo sapiens. That two-name system is also called binomial, because the idea is 'two names'. If you see the word in a science book about animals, that is why; the maths sense is the one this entry is for.

Though actually不過其實，the same word walks into biology同一個詞也會出現在生物學裡。Scientists name living things with two names科學家會用兩個名字來為生物命名，a group name and a species name一個屬名、一個種名：Homo sapiens像 Homo sapiens（智人）。That two-name system這種兩個名字的命名系統 is also called binomial也叫做 binomial（二名法），because the idea is 'two names'因為它的概念就是「兩個名字」。If you see the word in a science book about animals如果你在講動物的科普書裡看到這個詞，that is why原因就在這裡；the maths sense is the one this entry is for不過這篇詞條講的是數學上的那個意思。

The history is a bit cloudy. Late Latin had binōmium; English added -al. A 12th-century translator, Gerard of Cremona, used the Latin word when working from Arabic on Euclid, matching a Greek phrase that means 'from two names'. Where binōmium itself came from, scholars are not sure — perhaps Latin nōmen, 'name', perhaps another path. On the surface, English now feels it as bi- 'two' + -nomial 'name/term'.

The history這個字的來歷 is a bit cloudy有點模糊不清。Late Latin had binōmium晚期拉丁文有 binōmium 這個字；English added -al英文後來加上了 -al。A 12th-century translator, Gerard of Cremona十二世紀有位翻譯家 Gerard of Cremona，used the Latin word用了這個拉丁文字 when working from Arabic on Euclid在把歐幾里得的著作從阿拉伯文翻譯過來的時候，matching a Greek phrase that means 'from two names'對應到一個希臘文片語，意思是「從兩個名字而來」。Where binōmium itself came frombinōmium 這個字本身是哪裡來的，scholars are not sure學者們並不確定——perhaps Latin nōmen, 'name'也許來自拉丁文 nōmen，也就是「名字」，perhaps another path也許是別的來路。On the surface從表面上看，English now feels it as bi- 'two' + -nomial 'name/term'現在的英文會把它感覺成 bi-「二」加上 -nomial「名字／項」。