/ ˈgɒsəmə(r); NAmE ˈgɑːs-/ noun [ U ]
1.
the very fine thread made by spiders
2.
( literary ) any very light delicate material :
a gown of gossamer silk
the gossamer wings of a dragonfly
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WORD ORIGIN
Middle English : apparently from goose + summer , perhaps from the time of year around St Martin's summer, i.e. early November, when geese were eaten (gossamer being common then).