What term refers to a virus?

The term "viral" is directly associated with viruses, as it is derived from the Latin word "virus," which means poison or toxic substance. In medical terminology, "viral" is used to describe diseases or infections that are caused by viruses. For example, conditions such as influenza, HIV/AIDS, and the common cold are all referred to as viral infections due to the involvement of viruses as the causative agents of these diseases.

The other terms do not relate to viruses in the same way. "Virile" refers to manliness or strength, particularly in the context of masculinity. "Vascular" relates to blood vessels and the circulatory system, often involving terms around anatomy and physiology. "Vocal" pertains to voice or sound production related to speech. Therefore, "viral" is the specific term that associates with viruses, making it the correct choice in the context of this question.