Picture a small closed case that you never open yourself. Something delicate is already inside it — tape, film, a set of metal rings — packed as one tidy unit. You slide the whole case into a machine, and the machine does the handling for you.
可以想成一個你自己不會打開的小盒子。裡面已經裝好一樣不方便用手碰的東西：磁帶、底片，或一整組齒片。它被整理成一整塊，你只要把整個盒子推進機器，剩下的交給機器處理。這個字的每一種用法，幾乎都可以回到這個畫面：整組裝進去、整組拿出來。
From the word’s history
Borrowed from French cassette, from Latin capsa (a box), with the French ending -ette marking something small — literally a little box.
借自法文 cassette，再往上是拉丁文 capsa（箱子、盒子），法文字尾 -ette 表示「小」。字面上就是「小盒子」，跟今天每一種用法的畫面對得上。
Wiktionary entry supplied in packet (source_ref kaikki:3f6f69a190036ae4:961187447:45601), etymology tree Latin capsa > Old French -ete > French cassette.
登入就可以看每一支怎麼連回核心畫面。