a. a young dog, esp when under one year of age; puppy
b. the young of various other animals, such as the seal
2.in pup (of a bitch) pregnant
(Potentially Unwanted Program) An application that is installed along with the desired application the user actually asked for. Also called a "barnacle," in most cases, the PUP is spyware, adware or some other unwanted software. However, what makes spyware or adware a PUP rather than pure malware is the fact that the end user license agreement (EULA) does inform the user that this additional program is being installed. Considering hardly anyone ever reads the license agreement, the distinction is a subtle one. See spyware, adware and malware.