Curtain off refers to the act of separating or dividing an area using a curtain or similar material. There are several synonyms that can be used in place of curtain off, including partition, divide, separate, isolate, block, fence, close off, and barricade. These words all describe the action of creating a physical barrier or boundary to separate one space from another. Other related words might include screen, shield, cover, or veil. Depending on the context and intended meaning, any of these words might be a suitable replacement for the phrase curtain off.