The word "poisonousness" refers to the quality or state of being poisonous. There are several synonyms for this word. One of them is toxicity, which refers to the degree to which a substance is harmful. Another synonym is venomousness, which refers specifically to the property of venom, a toxic substance produced by certain animals. Additionally, the word virulence can also be used as a synonym for poisonousness, particularly in medical contexts where it refers to the ability of a pathogen to cause disease. Other synonyms include deadliness, lethality, and hazard. All of these words convey the same meaning as poisonousness and can be used interchangeably depending on the context.