gossamer (n.)

c. 1300, "filmy substance (actually spider threads) found in fields of stubble in late fall," apparently from gos "goose" (see goose (n.)) + sumer "summer" (see summer (n.)). Not found in Old English. The reference might be to a fancied resemblance of the silk to goose down, or more likely it is shifted from an original sense of "late fall; Indian summer" because geese are in season then. Compare Swedish equivalent sommartrad "summer thread," Dutch zommerdraden (plural). The German equivalent mädchensommer (literally "girls' summer") also has a sense of "Indian summer," and there was a Scottish go-summer "period of summer-like weather in late autumn" (1640s, folk-etymologized as if from go). Thus the English word originally might have referred to a warm spell in autumn before being transferred to a phenomenon especially noticeable then. Compare obsolete Scottish go-summer "period of summer-like weather in late autumn." Meaning "anything light or flimsy" is from c. 1400; as a type of gauze used for veils, 1837. The adjective sense "filmy, light as gossamer" is attested from 1802.