The phrase "natural defense" refers to the body's ability to protect itself from harm, such as fighting off diseases or healing wounds on its own without the need for medication or external help. Full definition
A fever helps the body fight infections by stimulating natural defense mechanisms. (kidshealth.org)
Our immune systems are our body's natural defense against illness and disease. (fitnessandpower.com)
The cells have natural defense system against free radicals and can repair themselves from the damage caused by the dangerous substances. (giendoscopypractice.com)