Preservative (noun)

1. A substance added to food or other perishable items to prevent decay and deterioration.
2. A substance used to preserve dead specimens or other organic material.
3. A substance added to paint, varnish, or similar materials to increase their shelf life.

Origin:

Late 16th century (as a adjective in the sense "preventing decay or preservation"): from late latin preservativus, from the verb preservare (see preserve).

Examples:

1. The food preservative, sodium benzoate, is added to this fruit juice to keep it fresh.
2. The Museum uses formaldehyde as a preservative for the dead specimens.
3. Adding a preservative to this paint will help it to last longer in storage.
4. Many food preservatives have been linked to various health problems.
5. The use of natural preservatives in food products is becoming more popular.