Definition: The word 'antisepsin' comes from Greek and means 'antibody'. It refers to a protein that helps our immune system fight bacteria, viruses or other pathogens by attaching onto them. Detailed definition: Anti-sepsin (Greek): Antimicrobial Antibody Definition: Anti-sepsin is a protein that the immune system uses to help fight off infections. In bacteria and certain viruses, it can be used to kill them. It works by binding to specific antigens on infected cells, preventing them from multiplying.