One way to picture slinky: something travelling along the surface of something else with no gap in between and no noise — a cat sliding along a wall, a spring pouring itself down a step, cloth running down over a shoulder. Nothing jumps, nothing sticks out, one part flows into the next.
Wiktionary gives slinky as slink + -y, so the adjective starts from the verb's picture of moving smoothly and quietly along.
供應的資料寫著 slinky 來自 slink 加字尾 -y。也就是說，形容詞是從「悄悄貼著滑過去」這個動作長出來的。後面講衣服、講音樂的用法，都可以看成同一個動作換了對象。
Wiktionary entry for slinky (adj), source_ref kaikki:3f6f69a190036ae4:602550868
Two branches
貼著身體滑下來的布
把「貼著滑」的動作交給布料。布不撐開、不站著，而是順著身體流下去，於是身體的線條跟著看得見，這就帶出性感的暗示。
adjective · C2
A slinky dress, skirt or top is made of soft, smooth cloth that hangs close to the body and follows its shape, in a way that looks sexy. It is usually said about women's clothes.
貼身滑順的
壓低身子悄悄移動
這一支最靠近動詞 slink 本身，是整個字最原始的落點：貼著牆、壓低、不出聲。
adjective · C2
Moving in a quiet, smooth, low way, like a cat that does not want to be seen. Said about a person or an animal, and it often suggests the person is not being open with you.
躡手躡腳的；像貓一樣悄悄的