- barrier - a structure or object that impedes free movement
--1 is a kind of obstruction, obstructor, obstructer, impediment, impedimenta
--1 has particulars:bannister, banister, balustrade, balusters, handrail; barricade; breakwater, groin, groyne, mole, bulwark, seawall, jetty; bulwarks, bulwark; crash barrier; dam, dike, dyke, levee; fence, fencing; fender, wing; grate, grating; hurdle; movable barrier; railing, rail; revetment; roadblock, barricade; starting gate, starting stalls - barrier, roadblock - any condition that makes it difficult to make progress or to achieve an objective; "intolerance is a barrier to understanding"
--2 is a kind of obstacle, obstruction
--2 has particulars: ideological barrier; language barrier- barrier - anything serving to maintain separation by obstructing vision or access
--3 is a kind of mechanism
--3 has particulars: bar; blood-brain barrier; curtain - barrier, roadblock - any condition that makes it difficult to make progress or to achieve an objective; "intolerance is a barrier to understanding"