A skein is a loosely coiled bundle of yarn or thread. When you buy yarn for knitting or crocheting, it often comes wound into a skein: a long, continuous strand looped and twisted into an oblong shape that's easy to store and use. If you've ever watched someone knit a sweater, they're probably pulling yarn from a skein that sits in their lap or a nearby basket.

The word also describes something long and tangled that resembles a coiled bundle of yarn. You might see a skein of geese flying in their distinctive V-formation across the autumn sky. Writers sometimes describe a skein of lies when someone has told so many falsehoods that they're all tangled together, or a skein of complications when a problem has many twisted, interconnected parts.

The image is always of something long and continuous that loops or coils: like yarn wrapped around itself, or geese stretched across the horizon in a long, connected line. When you untangle a skein of yarn to start a knitting project, you're literally unwinding those loops to find where the strand begins.