A Confederate soldier during the US Civil War (because of the grey uniforms).(noun)
A louse.(noun)
A local name for various grey birds.(noun)
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Use "greyback" in a sentence
"The rasp of his own "greyback" shirt and the squeak of his boots seemed to bring him to himself."
"Originally from South America, cane toads were imported to Australia in 1935 in an attempt to rid the country of the greyback beetle, which was destroying the sugarcane crop."
"Threading her way through the crowded streets, heeding not the jeers or insults of the rebel soldiery, she soon came in front of the Cooper Mansion, to find a rebel flag floating from an upper window, and a well dressed soldierly looking greyback, with bayonet fixed, pacing his beat in front."