The term 'PREFIX WITH VIRUS' can be solved by the crossword solutions 'ANTI' (4 letters) and 'RHINO' (5 letters). The prefix 'ANTI' is derived from the Greek word 'ANTI, ' meaning 'AGAINST, ' and is used to describe something that is opposed to or counteracts something else. The prefix 'rhino' is derived from the Greek word 'rhin, ' meaning 'NOSE, ' and is used to describe something that is related to the NOSE or has a NOSE-like shape. When combined with the word 'VIRUS, ' these prefixes create words such as 'antivirus' and 'rhinovirus, ' which refer to software or viruses that are designed to protect AGAINST or cause respiratory illnesses, respectively.