line backer is a noun meaning "a defensive football player who takes a position close behind the linemen". It carries 2 recorded senses.
a defensive football player who takes a position close behind the linemen
(American football) the position of a defensive football player who plays close behind the line of scrimmage
Definitions, synonyms and semantic relations for line backer come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.