ANTIGEN -
Noun: Antigens are any substance (usually a protein) whichthe body recognises as different from any natural body protein, such as viruses, fungi, bacteria, and some nonliving substances such as toxins, chemicals, drugs, and foreign particles. Once the immune system recognises an antigen, it produces antibodies that destroy the substance.

Greek - anti = opposing +

Greek - genês = born or something produced

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