Something symmetrical has matching halves — you could fold it down the middle and the two sides would lie exactly on top of each other. A butterfly. A human face, roughly. The letter A. A well-planned garden with the same three trees on each side of the path. The everyday meaning is that mirror one.

Something symmetrical has matching halvessymmetrical指的是兩邊一模一樣——you could fold it down the middle把它從中間對折 and the two sides would lie exactly on top of each other兩邊會完全疊在一起。A butterfly像蝴蝶。A human face, roughly大致上人臉也是。The letter A字母A也是。A well-planned garden with the same three trees on each side of the path規劃良好的花園，小徑兩邊各種著一樣的三棵樹，也是。The everyday meaning is that mirror one日常生活裡說的就是這種左右對稱的意思。

Maths adds more kinds: rotational symmetry, where a shape looks the same after you turn it part of the way round (a five-pointed star, a snowflake); point symmetry; symmetry across more than one line. So a mathematician calling something symmetrical may not mean left-and-right at all. And the word travels well beyond shapes: a symmetrical argument treats both sides by the same rule, a symmetrical trade agreement gives each country the same terms, symmetrical warfare means two sides fighting with comparable weapons — which is why the news says asymmetrical warfare for the other case.

Maths adds more kinds數學裡還有更多種類：rotational symmetry旋轉對稱，where a shape looks the same after you turn it part of the way round指一個形狀轉一部分角度之後看起來還是一樣 (a five-pointed star, a snowflake)（像五角星、雪花）；point symmetry還有點對稱；symmetry across more than one line以及跨越不只一條線的對稱。So a mathematician calling something symmetrical所以數學家說某個東西symmetrical may not mean left-and-right at all可能根本不是指左右對稱。And the word travels well beyond shapes而且這個字用的範圍也遠超過形狀：a symmetrical argument treats both sides by the same rulesymmetrical argument指雙方都用同一套規則對待，a symmetrical trade agreement gives each country the same termssymmetrical trade agreement指給每個國家一樣的條件，symmetrical warfare means two sides fighting with comparable weaponssymmetrical warfare指雙方用差不多的武器打仗——which is why the news says asymmetrical warfare for the other case這也是為什麼新聞會用asymmetrical warfare來說另一種情況。

The opposite words matter here. Asymmetrical means the halves do not match. Unsymmetrical exists but sounds clumsy; native speakers reach for asymmetrical. In fashion and design, asymmetrical is often a compliment — an asymmetrical haircut is deliberate.

The opposite words matter here反義字在這裡很重要。Asymmetrical means the halves do not matchasymmetrical指的是兩邊不對稱。Unsymmetrical exists but sounds clumsyunsymmetrical這個字也存在，但聽起來很彆扭；native speakers reach for asymmetrical母語人士會選用asymmetrical。In fashion and design在時尚設計裡，asymmetrical is often a complimentasymmetrical常常是稱讚——an asymmetrical haircut is deliberate不對稱的髮型是刻意設計的。

Though actually — be careful with 'perfectly symmetrical', because almost nothing real is. Faces are close but not equal, and studies keep finding that people rate slightly imperfect faces as more attractive, not less. Buildings that look symmetrical are usually adjusted by hand so they will look right rather than measure right. So in careful writing you will see hedges: roughly symmetrical, near-symmetrical, symmetrical at first glance. The word describes an ideal that objects approach.

Though actually不過話說回來——be careful with 'perfectly symmetrical'要小心'perfectly symmetrical'這種說法，because almost nothing real is因為現實中幾乎沒有東西真的完全對稱。Faces are close but not equal人臉很接近但並不相等，and studies keep finding that people rate slightly imperfect faces as more attractive, not less而研究一直發現，人們覺得稍微不對稱的臉更有吸引力，而不是比較沒吸引力。Buildings that look symmetrical看起來對稱的建築 are usually adjusted by hand so they will look right rather than measure right通常是靠人工調整過，為了讓它看起來對，而不是量起來對。So in careful writing所以在講究的文章裡 you will see hedges你會看到保留的說法：roughly symmetrical, near-symmetrical, symmetrical at first glanceroughly symmetrical、near-symmetrical、symmetrical at first glance。The word describes an ideal that objects approach這個字描述的是一種物體只能趨近、達不到的理想狀態。

One more thing worth knowing: symmetrical and symmetric mean the same thing, and both are correct. Symmetric is preferred in mathematics and physics (a symmetric matrix), symmetrical in ordinary description. Do not spend energy choosing; do not use both in one paragraph.

One more thing worth knowing還有一件事值得知道：symmetrical and symmetric mean the same thingsymmetrical跟symmetric意思一樣，and both are correct兩個講法都對。Symmetric is preferred in mathematics and physicssymmetric在數學和物理裡比較常用 (a symmetric matrix)（像a symmetric matrix），symmetrical in ordinary description一般描述則用symmetrical。Do not spend energy choosing不用花心思去挑，do not use both in one paragraph但同一段裡不要兩個都用。