Scareware is software that flashes false warning messages — “Your computer is infected!” — so that you panic and buy antivirus (or type in a card number) that you do not actually need. The “problem” is fake or hugely overstated. The word is scare plus the -ware you hear in software. It belongs to tech-news and computer-security talk; people who work with computers often just keep the English word. Related nasties include malware (software meant to harm) and ransomware (software that locks your files until you pay). Real antivirus warnings exist too; scareware is the dishonest kind that lives on the fear.