那把會轉彎的鋸子，和用它切東西
核心畫面本身：窄刀片、快速上下、可以一路轉彎。
noun · B2
A power tool with a short, narrow blade that moves quickly up and down, used for cutting curves and shapes out of thin wood or metal.
曲線鋸；線鋸機
核心畫面
Picture a short, narrow blade going up and down very fast, and a hand turning a board against it so the cut can wander wherever the pencil line goes. That is what this word is built around: not a straight cut, but a wandering one. Everything else in the word comes from what such a cut leaves behind — edges that curve in and out, so that two pieces only sit together one way. A picture cut like that becomes a game. A situation whose facts only match up one way gets called by the same name.
可以想成一片又短又窄的刀片，正在飛快地上下抽動，而一隻手轉動著木板送上去，讓切口一路跟著鉛筆線彎來彎去。這個字的核心…更多收起
可以想成一片又短又窄的刀片，正在飛快地上下抽動，而一隻手轉動著木板送上去，讓切口一路跟著鉛筆線彎來彎去。這個字的核心就在這裡：不是筆直的一刀，而是會轉彎的一刀。其他意思都可以想成從這種切口留下的東西長出來——邊緣凹凹凸凸，兩片只有一種方式對得上。一張圖被這樣切開，就成了遊戲；一件事情的線索也只有一種對法時，英文就借同一個字來說它。From the word’s history
Wiktionary gives the same origin for both the noun and the verb: jigsaw is jig + saw. The packet does not go further than that, so the link between the tool and the picture game is offered here as a way of understanding the word, not as a documented history.
字典對名詞和動詞給的是同一個來源：jigsaw 就是 jig 加 saw（鋸子）。手上的資料只寫到這一層，所以「工具和拼圖之間的關聯」在這裡是幫助理解的說法，不是有記載的歷史推演。
Wiktionary entries for jigsaw, noun and verb (supplied in evidence packet): "From jig + saw."
Two branches
切成一片片的圖，和像它一樣的難題
彎曲的切口留下彼此咬合的邊，於是「一片一片、只有一種對法」成了這一組的重點。這是理解上的連結，不是有記載的來源說明。
noun · B1
A picture on card or wood that has been cut into many small oddly shaped pieces, which you fit back together as a game; also called a jigsaw puzzle.
拼圖