Picture two ends that do not quite touch, and a soft metal that turns liquid before either of them does. The liquid runs into the gap, cools, and goes hard. Now there is no gap and no join you can pull apart — there is one piece. Everything the word does comes from that: the metal itself, the act of using it, and the picture writers borrow when two separate things end up holding as one.
可以想成兩個沒有完全接上的端點，加上一種比它們都先融化的軟金屬。液態的金屬流進縫隙，冷卻，然後變硬。縫隙不見了，也拉不開了——它們變成一塊。這個字的每個用法都從這裡出發：那個金屬本身、使用它的動作，還有作者借來形容「兩個分開的東西最後長成一體」的畫面。
From the word’s history
The supplied source takes it back through Old French to Latin solidare, to make solid — the same family as solid. That is exactly what the cooled joint does: it makes two loose parts into one solid thing.
本批資料所附的來源說明：經古法文回到拉丁文 solidāre（使變結實），跟 solid 是同一家人。這正是冷卻後的接點在做的事——把兩塊鬆開的零件變成結實的一塊。
Wiktionary, "solder"
登入就可以看每一支怎麼連回核心畫面。