小小一顆球
這是核心畫面最直接的一面：小小的一顆，翹在東西上面。
noun · B2
A small soft ball, usually made of wool, that is fixed to a hat, a scarf or other clothing to decorate it.
毛球
核心畫面
One way to hold this word: something small that will not sit still or will not lie flat. On a hat, the wool gathers into one little ball that sticks up. On an old sweater, the surface rolls itself into dozens of tiny balls. In a game, the ball keeps hopping in your hands instead of settling. On the water, a light thing keeps lifting and dropping. Small, round, and never quite still — that picture runs under every use.
一種想法是：bobble 講的都是「小小的、安分不下來的東西」。毛帽上那一撮毛線聚成一顆小球，翹在頂端。舊毛衣的表面…更多收起
一種想法是：bobble 講的都是「小小的、安分不下來的東西」。毛帽上那一撮毛線聚成一顆小球，翹在頂端。舊毛衣的表面自己捲出一顆顆小球。球到手上還在跳，就是不肯乖乖停住。東西浮在水上，一上一下被水推著走。小、圓、停不下來——這個畫面可以貫穿它所有用法。From the word’s history
Wiktionary records the noun as bob + -le (a diminutive ending) and the verb as bob + -le (a frequentative ending). Bob is a small quick up-and-down movement. So the noun side means a little thing, and the verb side means doing that little movement again and again.
來源資料把名詞記成 bob 加上表示「小」的字尾 -le，把動詞記成 bob 加上表示「反覆」的字尾 -le。bob 本身是「快速地上下動一下」。所以名詞這邊走向「小小一顆」，動詞這邊走向「一直小小地動」。這剛好解釋了為什麼同一個字既是毛球，也是晃動。
Wiktionary entry for bobble, packet source_ref kaikki:3f6f69a190036ae4:613188070:7343 — etymology_text: "(noun): from bob + -le (diminutive suffix). (verb): from bob + -le (frequentative suffix). Compare bauble."
Two branches
小幅度、抓不住的動
把核心畫面的「安分不下來」從形狀換成動作來看。
verb · C1
To move in small bouncy movements: going up and down in one place, or rolling slowly and unevenly along the ground.
上下晃動；一路滾滾停停