one of the paired, elongated, sickle-shaped, middle feathers of the tail of the rooster.
Origin of sickle feather
First recorded in 1680–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
(often plural) any of the elongated tail feathers of certain birds, esp the domestic cock
Word Origin for sickle feather
C17: so called because of its shape
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012