n.member of a secret mounted band in United States south after the American Civil War; committed acts of intimidation and revenge
同义词：night rider
英汉双解大词典
nightrider/ˈnaɪtˌraɪdə/
1.
N（名词）
a member of a band of mounted and usually masked White people in the southern US who carried out acts of revenge and intimidation at night after the Civil War 蒙面劫匪