地理上的前線：國界與邊疆
這一族就是那條線最原本、看得見的樣子：踩在地上、畫在地圖上的分界。
national border · noun · C2
The line that separates two countries, or the land near that line.
邊境
核心畫面
A line drawn at the front edge of settled land — beyond it, the map stops being yours.
一條畫在「已知世界最前面」的線。frontier 和 front(前面)同源，所以它天生帶著「前線」的感覺——線的這…更多收起
一條畫在「已知世界最前面」的線。frontier 和 front(前面)同源，所以它天生帶著「前線」的感覺——線的這一邊是你熟悉、已經管到的地方，另一邊是別人的、或還沒人踏進去的。站在那條線上往前看，前方是空白；回頭看，後方是家。國界之所以叫 frontier，就是因為那是「我們這一國最前面」的地方。From the word’s history
From Old French frontier, from front ("forehead, front, front line"): the frontier is literally the front edge of a territory.
來自古法語 frontier，源頭是 front(前額、前方、前線)。所以 frontier 從字面上就是「領土最前面的那一條」——這個 front 的意思一路留在現代三個用法裡：國界是政治上的最前線,邊疆是拓墾的最前線,而科學前沿是知識的最前線。
Wiktionary, "frontier" (Middle English frounter < Old French fronter/frontière < front)
Two branches
知識上的前線
把地圖換成「知識的版圖」,那條最前面的線就從土地搬到了學問上——一樣是邊緣,一樣還在往外推。
frontier of knowledge · noun · C2
The far edge of what people know or can do in a subject, such as science.
前沿
原始詞典資料11 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。
Frontiername
- 1
A place in the United States:
- 2
A place in the United States:
- 3
A place in the United States:
- 4
A place in the United States:
- 5
A village in Saskatchewan, Canada.
- 6
A rural municipality on the US border in south-west Saskatchewan, which includes the village; in full, the Rural Municipality of Frontier No. 19.
frontiernoun/ˈfɹʌntɪə/
- 1
The part of a country which borders or faces another country or unsettled region.
- the frontier of civilization
- There were not many passengers, and the journey was uneventful until the frontier was reached at Padang Besar, although an armed escort of Malay police accompanied the train from Alor Star.
- 2
The most advanced or recent version of something; the leading edge.
- Near-synonyms: vanguard, state of the art
- the frontier of solid state electronics
- 3
obsoleteAn outwork of a fortification.
- thou hast talk'd. Of sallies and retires, of trenches, tents, Of palisadoes, frontiers, parapets
frontierverb/ˈfɹʌntɪə/
- 1
To live as pioneers on frontier territory.
- 2
obsoleteTo place on the frontier.
- now that it is no more a Border, nor frontiered with Enemies, why should such Privileges be any more continued?
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。