幾何：四條直邊的圖形
這一支最貼近字面：四個角、四條邊，畫在紙上就是了。
noun · C1
A flat shape with four straight sides, such as a square, a rectangle, or any other four-cornered figure.
四邊形
核心畫面
One way to hold this word: four corners marking out a flat piece of ground. Draw those corners on paper and you have a four-sided figure. Build them at full size, and stand a row of buildings along each of the four edges, and the same four corners now hold an open courtyard. Move your eyes from the ground up to the walls, and the word can point at the ring of buildings instead. One picture, three places to look.
quadrangle 可以想成：四個角圈出一塊平面。把這四個角畫在紙上，得到的就是四邊形。把它放大到真實尺寸，四個邊…更多收起
quadrangle 可以想成：四個角圈出一塊平面。把這四個角畫在紙上，得到的就是四邊形。把它放大到真實尺寸，四個邊各立起一排樓房，同樣那四個角就圈出一座中庭。如果眼睛從地面往上移到牆面，這個字又可以指圍成中庭的那一整圈建築。三個意思其實共用同一張圖，差別只在你看的是線、是地、還是樓。From the word’s history
From Late Latin quadrangulum, through Old French and Middle English: quadr- (four) plus angulum (angle), literally a four-cornered thing. The four corners in the word are the four corners in every one of its uses.
來自晚期拉丁文 quadrangulum，經古法文和中古英文進入現代英文：quadr-（四）加 angulum（角），字面上就是「有四個角的東西」。字裡的那四個角，正是它每一個意思裡都看得到的四個角。
packet evidence: Wiktionary etymology_text for quadrangle (Middle English quadrangle < Old French quadrangle < Late Latin quadrangulum)
Two branches
建築：四面圍出的中庭，以及圍成它的樓
同樣四個角，但這次不是畫在紙上，而是用真實的樓房在地面上圈出來。圈出來的空地是一個意思，圈住它的那些樓是另一個意思。
noun · B2
An open square or rectangular piece of ground with buildings standing all around its four sides, especially at a school, a college, or a university.
中庭（方形庭院）