pack ratEnglishOxford New American Dictionarypack rat /ˈpak ˌrat, ˈpæk ˌræt / ▸ noun a ratlike rodent that accumulates a mound of sticks and debris in the nest hole, native to North and Central America. Also called wood rat. Neotoma and other genera, family Muridae: many species. ▪ North American derogatory a person who saves unnecessary objects or hoards things.