Any of various shearwaters and petrels of the North Atlantic, especially the greater shearwater, Ardenna gravis, and the sooty shearwater, A. griseus. Also occasionally: any of several other seabirds, as skuas and fulmars. Compare "hackbolt", haglet .
Late 17th century; earliest use found in James Yonge (1647–1721), surgeon and physician. Origin unknown.