n a line that marks the side boundary of a playing field
n an auxiliary line of merchandise
n an auxiliary activity
v remove from the center of activity or attention; place into an inferior position
n. 副业( sideline的名词复数 ); 兼职; （球场等的）边线; 两侧场外区域
v. 使退出比赛( sideline的第三人称单数 ); 使下场（尤指由于受伤）; 把…排除在核心之外; 使靠边