Picture a board fixed at one end with the other end hanging free. You step out, press down hard, and the board bends under your weight. Then it pushes back and throws you up, and in that same second you have already left it behind. Two things matter in this picture: the push is short, and you do not stay on the board.
可以想成一塊板子，一端固定，另一端懸空。你走上去，用力往下壓，板子在你的重量下彎了下去。接著它彈回來，把你往上送，而就在同一秒，你已經離開它了。這張畫面裡有兩件事最重要：那一下推力很短，而且你不會留在板子上。這個字後來所有的用法，都是從這兩件事長出來的。
From the word’s history
From spring + board: the board that springs. The compound says exactly what the object does, and both later uses keep it.
這個字就是 spring（彈）加 board（板子）合起來的，字面是「會彈的板子」。合成的名字把東西的功能直接說了出來，後面兩種用法也都還帶著它。
Wiktionary entry for springboard (packet source_ref kaikki:3f6f69a190036ae4:1223408526:19350)
登入就可以看每一支怎麼連回核心畫面。