真的往下栽：機頭朝下的那一段
這一組就是核心畫面本身，差別只在誰在掉、用名詞還是動詞來講。
noun · B2
A sudden, steep drop through the air made by a plane with its front end pointing down towards the ground.
俯衝
核心畫面
Think of the moment a plane tips its nose down and drops towards the ground. Not a slow, gentle descent, but head-first, steep and fast, the kind of fall that makes people catch their breath. Every use of nosedive can be held inside that one picture. What is dropping may be a plane, a person tripping forward, or a line on a sales chart, but the shape of the fall stays the same: nose first, straight down, and quicker than anyone expected.
可以想成一架飛機把機頭壓下去、整架往地面衝的那一瞬間：不是慢慢下降，而是頭先朝下，又快又陡，看的人會倒抽一口氣。no…更多收起
可以想成一架飛機把機頭壓下去、整架往地面衝的那一瞬間：不是慢慢下降，而是頭先朝下，又快又陡，看的人會倒抽一口氣。nosedive 的每一個用法，大致都能放進這個畫面裡。往下掉的可能是飛機，可能是絆倒往前撲的人，也可能是圖表上那條銷售曲線——但下墜的形狀都一樣：頭朝下，一路到底，而且比誰預期的都快。From the word’s history
Wiktionary records the word simply as 'nose + dive'. The two parts still say the whole picture: the nose goes first, and the movement is a dive — downward, steep and fast.
Wiktionary 記載 nosedive 由 nose 加 dive 組成。兩個字合起來就把畫面講完了：鼻子（機頭）在前，動作是 dive——往下、又快又陡。後來用在價格和狀況上的意思，借的就是這條下墜線。
Wiktionary entry 'nosedive' (packet source_ref kaikki:3f6f69a190036ae4:1215680536:8801): 'From nose + dive.'
Two branches
數字和狀況的暴跌
把飛機的下墜線畫到圖表上，就成了這一組意思。重點不是掉了多少，而是那條線的角度：陡、快、讓人措手不及。
noun · B2
A sudden, very large fall in the price, the value, or the condition of something, where the drop is fast and goes a long way down.
暴跌