看得見的來回：實體的擺動
這一組就是核心畫面本身，只是換了不同的東西在擺。
noun · C1
A regular movement of something from one side to the other and back again, repeated in the same way each time, like the swinging of a pendulum.
擺動、振盪
核心畫面
You can think of a pendulum hanging on a string. Push it once and it swings out to one side, comes back, and goes out to the other side. It keeps doing this, and each swing takes about the same time. Every meaning of oscillation seems to grow from that one picture: something moves out to one end, returns, and repeats. What changes from sense to sense is only what is doing the swinging — a hanging weight, a price on a chart, a person's mood, or the electric current inside a wire.
一顆掛在繩子上的鐘擺。推它一下，它盪到一邊，再盪回來，然後盪到另一邊。它就這樣一直來回，而且每一次花的時間都差不多。…更多收起
一顆掛在繩子上的鐘擺。推它一下，它盪到一邊，再盪回來，然後盪到另一邊。它就這樣一直來回，而且每一次花的時間都差不多。oscillation 的各種意思，就像都從這個畫面長出來：跑到一端、回來、再重複。不同的只是「在擺的是什麼」——可能是掛著的重物，可能是圖表上的價格，可能是一個人的心情，也可能是電線裡的電流。From the word’s history
Wiktionary records oscillation as coming from French oscillation, from Latin oscillatio and the Latin verb oscillo, and notes that in modern English it can simply be read as oscillate + -ion. The Latin verb is about swinging, which lines up with the swinging picture the modern word still carries.
依 Wiktionary 的記載，oscillation 來自法文 oscillation，再往前是拉丁文 oscillatio 與動詞 oscillo；就今天的英文來看，也可以直接拆成 oscillate 加上 -ion。拉丁文那個動詞講的就是擺動，正好和這個字今天仍然帶著的「來回」畫面對得上。
Wiktionary (kaikki:3f6f69a190036ae4:748241238:19832), etymology_text supplied in the evidence packet
Two branches
看不見的來回：數字與心情的擺盪
把鐘擺的軌跡畫成一條折線，上上下下的數字或心情，就成了同一個來回。
noun · C1
Repeated changes in an amount, price or level, going up to one extreme and then down to the other, again and again.
（數值的）來回波動