Gossamer describes something so light, thin, and delicate that it seems it might float away or disappear if you breathe on it. The word originally referred to the ultra-fine threads that spiders spin, the ones you see glistening with dew on an autumn morning, stretched between blades of grass like nature's own silk.

A ballerina's costume might be made of gossamer fabric that floats around her as she moves. A thin layer of clouds stretched across a blue sky could look gossamer. When you find a dandelion gone to seed, those white filaments that carry the seeds on the wind are like gossamer threads.

The word carries a sense of beauty along with delicacy. Something gossamer has an almost magical quality, like it belongs in a fairy tale. You might describe a memory as gossamer if it's precious but fading, or call an excuse gossamer if it's too flimsy to hold up under questioning.