Adenovirus: One of a group of viruses that can cause infections of the lung, stomach, intestine, and eyes. Symptoms resemble those of the common cold. There are no effective medications for treating adenovirus infection. Adenovirus infection typically does not cause death or permanent problems. More than 40 types of adenoviruses have been recognized, all of which are extremely tiny. Adenoviruses are being used in research as a vehicle for gene therapy and as a vector for vaccines.