Ludd can mean 'down', 'fluff', 'fuzz', or 'lint'. You get ludd when textile fibers or other materials bind together and create a fluffy material.
The reason we've chosen it as our word of the day might be clear if you've spent any time outdoors this week. Stockholm and other parts of Sweden have found themselves covered in a blanket of ludd that looks a bit like cotton wool or snow (if you squint a bit).
This particular type of ludd is caused by seeds from the aspen tree, which are dispersed in balls of ludd rather than as loose seeds, in order to help them move through the air and spread out.
Aspen ludd has been produced in record amounts this year, causing some Swedes to wonder why the forests and parks look as if there's been late May snow.
Although it's not a cause of hay fever, this ludd isn't entirely harmless, and can help grass fires and wild fires spread extremely quickly.
But you'll also use ludd to describe fluff made of manmade fibres, such as lint on an old jumper, balls of dust found in rarely-vacuumed corners of the apartment, or lint left in the filter of a tumble dryer – the latter can lead to serious arguments between neighbours in Sweden, where communal laundry rooms are the norm in apartment blocks, and you might find handwritten notes demanding Varför finns det alltid ludd i torktumlaren? (Why is there always fluff in the tumble dryer?).
Ludd finds its way into many compound words, such as navelludd (belly button fluff), fickludd (fluff found in your pocket) and of course torktumlarludd (tumble dryer lint).
And the word is related to the adjective luddig, which can mean 'fluffy/soft/fuzzy' and is often used metaphorically, for example det är en luddig definition (that's a fuzzy/unclear definition) or hans minne kunde vara luddigt (his memory could be fuzzy).
Another occasion when you might hear the word luddig in your everyday life is at the optician. When you're having your eyesight tested, the optician might ask if the letters look sharp or luddig (fuzzy) through different lenses.
So, it's a word that's especially useful this week, but could come in useful on many other occasions too.
Varför finns det så mycket vitt ludd i luften?
Why is there so much white fluff in the air?
Flickan letade under soffan men hittade bara ludd
The girl looked under the sofa but only found fluff