barbule
noun
bar·bule ˈbär-(ˌ)byül 
: a minute barb
especially : one of the processes that fringe the barbs of a feather see feather illustration
Example Sentences
Recent Examples on the Web Unlike in other shiny birds, such as hummingbirds or crows, the cassowary's glossiness is produced by the rachis, or the spine of the feather, rather than the barbules, or minute filaments fringing a feather. 
Katie Hunt, CNN, 13 May 2020 Those barbules, in turn, have even smaller features—lumpy nodes and prongs spaced along their length. Helen Czerski, WSJ, 6 Feb. 2020 Long curly barbs radiate out from the center, and each one is covered in smaller barbules that stick out like the branches on a fir tree. Helen Czerski, WSJ, 6 Feb. 2020 The contour feathers interlock and overlap with tiny barbs (actually called barbules), forming a water and windproof protective outer layer on their bodies. Cori Brown, baltimoresun.com/maryland/carroll, 20 Oct. 2019 Inside the feather’s barbules, layers of melanosomes and a type of the structural protein keratin can scatter incoming light in such a way that only certain colors reflect back out. Michael Greshko, National Geographic, 25 June 2019 Some bird of paradise feathers, on the other hand, are irregular, with curved, spiky barbules and cavities within the feathers. Brigit Katz, Smithsonian, 11 Jan. 2018 When light strikes a superblack feather's forest of barbules—which tilt at about 30 degrees toward the outer tip of the feather—it gets reflected into cavities between the tiny structures rather than outward, McCoy says. Sid Perkins, Scientific American, 9 Jan. 2018 See More
Katie Hunt, CNN, 13 May 2020 Those barbules, in turn, have even smaller features—lumpy nodes and prongs spaced along their length. Helen Czerski, WSJ, 6 Feb. 2020 Long curly barbs radiate out from the center, and each one is covered in smaller barbules that stick out like the branches on a fir tree. Helen Czerski, WSJ, 6 Feb. 2020 The contour feathers interlock and overlap with tiny barbs (actually called barbules), forming a water and windproof protective outer layer on their bodies. Cori Brown, baltimoresun.com/maryland/carroll, 20 Oct. 2019 Inside the feather’s barbules, layers of melanosomes and a type of the structural protein keratin can scatter incoming light in such a way that only certain colors reflect back out. Michael Greshko, National Geographic, 25 June 2019 Some bird of paradise feathers, on the other hand, are irregular, with curved, spiky barbules and cavities within the feathers. Brigit Katz, Smithsonian, 11 Jan. 2018 When light strikes a superblack feather's forest of barbules—which tilt at about 30 degrees toward the outer tip of the feather—it gets reflected into cavities between the tiny structures rather than outward, McCoy says. Sid Perkins, Scientific American, 9 Jan. 2018 See More Word History
First Known Use
1813, in the meaning defined above