1. The colorless or milky sap of certain plants, such as the poinsettia or milkweed, that coagulates on exposure to air.

2. A polymer emulsion consisting of such sap obtained from rubber trees, used to manufacture various thin elastic products such as balloons, disposable gloves, and medical and contraceptive devices. Some people are allergic to this substance. Also called natural rubber latex.

3. A similar material made from polymers derived from petroleum; synthetic latex.

4. Latex paint.