Clearly, the boundaries separating one 20th-century art movement from another are never firm.

Though no physical boundaries separated the two groups, they did not interact often.

But there are plenty of clues that more than just a political boundary separates the two families.

It forms the boundary separating the plant's inner cells from the external world.

Under the traditional European model, strict boundaries separated them.

The boundaries separating national cinemas are more porous than ever.

A twin boundary or composition surface separates the two crystals.

The cultural boundaries separating white Americans from other racial or ethnic categories are contested and always changing.

I was well aware of the boundary separating my jurisdiction from that of the police.

Certain boundaries separate the worlds from each other, making the various summoning techniques the only way to transport things between them.