虏 is a classical-era noun that historically referred to captives taken in war, and was also used as a derogatory term for northern non-Han peoples (北虏). In modern Chinese it appears almost exclusively in compounds like 俘虏 (prisoner of war) or 虏获 (to capture). The word carries strong historical and ethnocentric connotations; avoid using it lightly. Because of its layered meanings—ranging from 'prisoner of war' to a slur for foreign tribes—context is critical.