Adenovirus

Etymology
Adenovirus

adeno: "glandular" (from greek ἀδενοειδής (adenoids), meaning "glandular")

virus: "poisonous secretion" (from latin vīrus, meaning "venom" or "poisonous secretion")

Explanation
Adenoviruses, which carry double-stranded DNA, cause a variety of infections, including GI infections, lower respiratory tract infections, and upper respiratory tract infections, which includes the adenoids (tonsils), which are glandular (adeno) collections of lymphoid tissue. Viruses, being so small, might have been thought of before they were discovered, to be poisonous secretions (virus) of unknown origin, hence their name.