tackler
Word family
Synonym discussion
Sense: noun/1
All three words refer to players who try to stop an opponent from advancing, but they differ in scope and specificity. Tackler is a role-based term: it describes any player who performs a tackle, regardless of position or sport. Defender is broader still — it covers any player whose main job is to prevent scoring, whether through tackling, blocking, intercepting, or marking — and is common in soccer, basketball, and hockey. Linebacker is the narrowest: a named position in American football whose primary duty is to tackle runners and quarterbacks. In context, you can call a linebacker a tackler or a defender, but calling a soccer defender a linebacker would be incorrect. For example: 'The All Blacks have several strong tacklers in their back line' uses the general role; 'The linebacker read the play and made the tackle' names the position.
Etymology
Tackler comes from the verb tackle (originally meaning 'to grip or seize,' borrowed from Middle Dutch takel meaning 'ship's rigging' or 'pulley'), combined with the agent suffix -er, which turns a verb into a noun meaning 'a person who does that action.' The sports sense of tackle developed in the mid-1800s, and tackler followed soon after as a natural way to name the person performing the action.