[bar.ri.er] n [ME barrere, fr. MF barriere, fr. barre] (14c) 1 a: something material that blocks or is intended to block passage "highway ~s" "a ~ contraceptive" b: a natural formation or structure that prevents or hinders movement or action "geographic ~s to species dissemination" "~ beaches" "drugs that cross the placental ~"
2. pl, often cap: a medieval war game in which combatants fight on foot with a fence or railing between them
3: something immaterial that impedes or separates: obstacle "behavioral ~s" "trade ~s" "a ~ to honest communication"