IPA: /ˈθɪsəlˌdaʊn/
KK: /ˈθɪsəlˌdaʊn/
The soft, fluffy material that comes from the seeds of a thistle plant, which helps the seeds to float in the air.
In the autumn, the garden was filled with thistledown drifting through the breeze.
Thistledown is formed from "thistle" (from Old English *þistel*, meaning a prickly plant) and "down" (from Old English *dūn*, meaning soft, fine hair or fluff). The word refers to the soft, fluffy seeds of the thistle plant.
Think of the prickly plant 'thistle' and its soft, fluffy 'down' — that's why thistledown refers to the soft seeds of the thistle.
No commonly confused words.