Which word means extremely infectious or poisonous, often used to describe a hostile attitude?

The term "virulent" is used to describe something that is extremely infectious or poisonous, particularly in the context of viruses or pathogens. Additionally, it can apply to behaviors or attitudes that are intensely hostile or aggressive. When referring to a hostile attitude, "virulent" emphasizes the strength and severity of that negativity, suggesting it can spread like a contagion or has a severe impact on those affected by it.

The other terms, while also related to hostility, have slightly different connotations. "Vitriolic" refers specifically to harsh and bitter criticism, often with a biting tone, but does not inherently convey the idea of contagion or poison. "Truculent" describes a fierce or aggressive attitude without the implication of infectiousness. "Vituperative" pertains to harsh and abusive language but lacks the association with physical contagion or toxicity implied by "virulent." Thus, "virulent" is the most fitting choice for describing a term that encompasses both extreme infectiousness and a profoundly hostile attitude.