L0181800 (līn′băk′ər)n. Abbr. LBFootball Any of the defensive players forming a second line of defense behind the players on the line of scrimmage.line′back′ing n.
linebacking
(ˈlaɪnˌbækɪŋ) nthe act of forming a second line of defence, close to the linesmanThesaurusSeelinebacker