Neutralizing serum

ANTITOXIN

Think of a medical substance that counters poisonous effects, often derived from antibodies to fight venom or bacterial toxins. Doctors might administer it after a snakebite.

"Neutralizing serum" points to a substance that counters toxins, which is exactly what an antitoxin does—it’s a biological preparation used to neutralize harmful poisons in the body. The word itself is straightforward: "anti" means against, and "toxin" refers to the poison, so the answer fits both the definition and the medical context. No wordplay here, just a direct clue matching a scientific term.