"Enforcer is an unofficial role in ice hockey. The term is sometimes used synonymously with "fighter", "tough guy" or "goon".
An enforcer's job is to deter and respond to dirty or violent play by the opposition. When such play occurs, the enforcer is expected to respond aggressively, by fighting or checking the offender. Enforcers are expected to react particularly harshly to violence against star players."
Video: Interview with an enforcer