IPA: /ˈlaɪnˌbækər/
KK: /ˈlaɪnˌbækər/
A player in football who plays behind the defensive line and is responsible for stopping the opposing team's running plays and defending against short passes.
The linebacker made a crucial tackle that stopped the opposing team from scoring.
Linebacker → The word is formed from "line" (from Old English *līne*, meaning a row or series) and "backer" (from the verb "to back", meaning to support or assist). A linebacker is a player who supports the defense behind the line of scrimmage.
Think of a player who is positioned behind the 'line' and is there to 'support' the defense — that's what a linebacker does.
No commonly confused words.