If "tarpaulin" refers to the material:
* Fabric: A general term for cloth, without the waterproofing or heavy-duty connotations of tarpaulin.
* Canvas: A type of fabric that is often used for sails and tents, but not necessarily waterproof.
* Thin material: This could be a synonym for "fabric," or something more specific like "paper" or "plastic."
If "tarpaulin" refers to its function:
* Exposure: The opposite of covering or protecting something.
* Transparency: The opposite of blocking light or rain.
* Ventilation: The opposite of creating a sealed, airtight environment.
Other options:
* Openness: This can be a general opposite to the idea of covering something up.
* Unprotected: This describes something that is not covered or shielded.
The best antonym will depend on the specific context in which you are using the word "tarpaulin."