[UNDER-1 5 c.] The down below the outer feathers of birds.
1842. J. B. Fraser, Mesopot. & Assyria, xv. 363. Cold winters … have every where the effect of lengthening the hair or fleece of animals, or of supplying them with an under-down.
1857. Dufferin, Lett. High Lat. (ed. 3), 42. Where the eider ducks … build nests with the soft under-down plucked from their own bosoms.
