Cases of word usage

1) a barrier of objects (e.g. sacks of sand) put in front of something as a defence (barricade)

2) a line, rope, ring of officials etc used as a barrier (cordon)

3) a barrier made of wood or wire, used round a garden etc or to divide two areas (fence)

4) an opening in a hedge, fence, wall etc able to be closed by a barrier; a barrier used to control the passage of water, e.g. into or out of a dam (gate)

5) a wall or barrier across a river or canal used to control the flow of water (weir)