實物：矛最前端的尖頭
字面本身，其餘用法都從這裡長出來。
noun · B2
The sharp pointed piece, usually of metal or stone, fixed on the end of a spear.
矛頭；槍尖
核心畫面
One way to hold this word: a spear is a long pole that does nothing on its own, plus one small hard point at the end that does everything. The point touches first, opens the way, and the whole length follows through the hole it made. Every other use is that point, moved somewhere else. A group at the front of a movement is the point. A person who gets a stuck project moving is the point, in verb form.
spearhead 可以想成一支矛的構造：長長的桿子自己什麼也做不到，真正起作用的是末端那一小塊又硬又尖的東西。它先…更多收起
spearhead 可以想成一支矛的構造：長長的桿子自己什麼也做不到，真正起作用的是末端那一小塊又硬又尖的東西。它先碰到目標，先破開阻力，後面整支矛才順著那個口子進去。其他所有意思，都是把這個「尖端」搬到別的地方。站在運動最前線的那群人，是尖端。把卡住的案子推動起來的人，也是尖端，只是換成動詞說。From the word’s history
From Middle English spere-hed, equivalent to spear plus head. Head here means the front end of a thing, as in the head of a line, not a person's head.
來自中古英文 spere-hed，等於 spear（矛）加 head（頭）。這裡的 head 不是人的頭，而是「一樣東西的最前端」，跟 the head of the line（隊伍最前面）是同一個用法。
packet evidence: Wiktionary etymology_text for spearhead (From Middle English spere-hed; equivalent to spear + head)
Three branches
帶頭的人或單位
把尖端換成人：位置最前、先開路，後面的人跟著走。
noun · B2
The person, group, or unit at the front of an attack or an organized effort, who lead it and go first.
先鋒；主力（帶頭的人或單位）
帶頭去做
同一個畫面改用動詞說：不只是名義上領導，而是站在最前面把事情往前推。
verb · B2
To lead an attack or an organized effort such as a campaign or a project, going in front and pushing it forward.
帶頭推動；主導