What is Enemy ?
Enemy is (noun) 1. a person who hates you Did your husband have many enemies? (NOTE: The plural is enemies.) 2. the country or people fighting against you in a war They attacked enemy airfields with bombs. The enemy has or have advanced to three kilometres from the city. (NOTE: The plural is enemies. In this meaning the singular form enemy can take a singular or plural verb.)
source: Easier English, Student Dictionary Upper Intermediate Level