抽象的層次
把「平面」往抽象方向搬：一個平面有它的高度，於是 plane 也指思考、談話、品質所處的「層次、水平」。就像把不同的平面一層層疊起來，你可以說某件事在更高的 plane 上。
plane (level of quality or thinking) · noun · A1
A level or standard of thinking, talking, or quality.
層次
核心畫面
A perfectly flat, level surface stretching out smooth in every direction — no bumps, no slope. From this one idea of 'flat and level' most of the meanings grow.
可以想成一個完全平坦、向四面伸展的平面——沒有起伏、沒有坡度，光滑齊整。plane 多數用法都是從這個「平、齊、無起…更多收起
可以想成一個完全平坦、向四面伸展的平面——沒有起伏、沒有坡度，光滑齊整。plane 多數用法都是從這個「平、齊、無起伏」的畫面長出來的（拉丁文 planus 就是平的）；只有「行道樹」那一支是另一條完全不同的路。From the word’s history
Most senses come from Latin 'planus' (level, flat); the flat-surface sense was coined in the 1600s to separate the geometric meanings from 'plain'. The aircraft sense is a shortening of 'aeroplane', named for its flat wing-surfaces. The 'plane tree' is unrelated, from Greek 'platanos' (from 'platys', broad), referring to its broad leaves.
大部分用法都來自拉丁文 planus（平、齊）；「平面」這個幾何義是 17 世紀為了跟 plain 區分而另造的。飛機義是 aeroplane（飛行平面，指機翼那片平展的面）縮短而來。但「懸鈴木（行道樹）」這一支與前面無關，來自希臘文 platanos（源自 platys「寬廣」），指它寬大的葉子。
etymonline.com (plane)
From the picture
刨平木頭的工具與動作
也扣著「平」：刨子是把木頭弄平的工具，它做的事就是製造出一個平面。所以名詞（刨子）和動詞（刨木頭）都圍著「把表面弄平」這個動作。
plane (woodworking tool) · noun · A1
A tool with a flat bottom and a sharp blade, used to make wood smooth.
刨子
飛機（機翼那片平展的面）
看似跳出「平」，其實仍連著：plane 是 aeroplane（aero「空氣」+ plane「平面」）的縮寫，名字指的就是機翼那兩片平展的承力面。對學習者來說它早已是獨立的日常字，所以另立一支，但根還在那片「平面」上。
plane (aircraft) · noun · A1
A vehicle that flies in the air, with wings and one or more engines.
飛機
Also in this word
plane (flat surface, geometry) · noun · A1
A completely flat surface, especially in maths and geometry.
平面
plane (flat, technical) · adjective · A1
Completely flat and smooth — a technical word used in maths and science.
平的
plane (tree) · noun · A1
A tall tree with broad leaves and bark that peels off, often planted along city streets.
懸鈴木
原始詞典資料16 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
planeadj詞源 1/pleɪn/
- 1
Of a surface: flat or level.
planenoun詞源 1/pleɪn/
- 1
A level or flat surface.
- 2
geometrymathematicssciencesA flat surface extending infinitely in all directions (e.g. horizontal or vertical plane); a bounded portion thereof.
- Mirrors in the compartments have been canted out of the vertical plane to reduce reflections to the passengers when seated.
- 3
anatomygeometrymathematicsA flat surface extending infinitely in all directions (e.g. horizontal or vertical plane); a bounded portion thereof.
- 4
A level of existence or development.
- astral plane
- Nettie's stories about her experiences in Africa point out many parallels between the African and American ways of life. Her stories about the African lifestyle and family structure, in particular, point out the sexist and oppressive conditions that women are forced to submit to on a global plane.
- 5
A roughly flat, thin, often moveable structure used to create lateral force by the flow of air or water over its surface, found on aircraft, submarines, etc.
- 6
computingengineeringmathematicsAny of 17 designated ranges of 2¹⁶ (65,536) sequential code points each.
planenoun詞源 2/pleɪn/
- 1
businesscarpentryconstructionA tool for smoothing wood by removing thin layers from the surface.
planeverb詞源 2/pleɪn/
- 1
businesscarpentryconstructionTo smooth (wood) with a plane.
planenoun詞源 3/pleɪn/
- 1
An airplane; an aeroplane.
- on a plane
- The plane is travelling impossibly slowly – 30km an hour – when it gently noses up and leaves the ground. With air beneath them, the rangy wings seem to gain strength; the fuselage that on the ground seemed flimsy becomes elegant, like a crane vaunting in flight. It seems not to fly, though, so much as float.
- 2
biologyentomologynatural-sciencesAny of various nymphalid butterflies, of various genera, having a slow gliding flight.
- 3
biologyentomologynatural-sciencesThe butterfly Bindahara phocides, family Lycaenidae, of Asia and Australasia.
planeverb詞源 3/pleɪn/
- 1
nauticaltransportTo move in a way that lifts the bow out of the water.
- 2
To glide or soar.
planenoun詞源 4/pleɪn/
- 1
A deciduous tree of the genus Platanus.
- 2
A sycamore.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。