樹幹外面那層皮
同一件外衣，這次穿在樹上。從字源看，這其實是這個字最早穿的那一件。
noun · C1
The outer layer of a tree trunk or branch: the hard skin on the outside of the wood.
樹皮
核心畫面
A picture worth holding: something soft with a hard coat over it. Inside is the part that is alive or good to eat, and around it sits a layer that is thicker, drier and tougher, keeping out the weather and the knocks. Rind is always that layer, never what is under it.
可以想成這樣一個畫面：軟的東西外面套了一件硬外衣。裡面是能吃的、活的部分，外面那層比較厚、比較乾、比較韌，擋著風、水…更多收起
可以想成這樣一個畫面：軟的東西外面套了一件硬外衣。裡面是能吃的、活的部分，外面那層比較厚、比較乾、比較韌，擋著風、水和碰撞。rind 指的一直是那件外衣，不是外衣底下的東西。From the word’s history
Old English rind and rinde meant tree bark or crust, and German Rinde still means bark today. The word began as the coat on a tree and the same coat was later seen on fruit and cheese.
古英語的 rind／rinde 就是「樹皮、外殼」，今天的德文 Rinde 還是樹皮。這個字一開始講的是樹的外衣，後來同一件外衣被看在水果和乳酪上。
Wiktionary etymology supplied in this packet (kaikki:3f6f69a190036ae4:379949250:21044)
From the picture
Also in this word
noun · B1
The thick outer skin of some fruits, such as oranges, lemons, or watermelons, which you usually cut off or grate instead of eating with the fruit.
果皮（厚而硬的外皮）
noun · B1
The firm outer layer on some foods such as cheese or bacon, harder than the part inside and often cut away before or after cooking.
外皮（乳酪、培根等食物的）