en·e·my 
/ˈɛnəmi/ noun
plural en·e·mies /ˈɛnəmi/ noun [count] 1 : someone who hates another : someone who attacks or tries to harm another
▪ They are sworn/bitter enemies. ▪ He made a lot of enemies during the course of his career. ◊If you are your own worst enemy you act in a way that causes harm to yourself or to the people or things that you care about. 2 : something that harms or threatens someone or something
▪ Tradition is the enemy of progress. ▪ In many countries today, drug abuse is public enemy number one. [=the most dangerous threat to society] 3 a : a group of people (such as a nation) against whom another group is fighting a war — usually singular ▪ Some of the soldiers went over to the enemy. ▪ He found himself behind enemy lines. ▪ The plane was shot down by enemy fire.
b : a military force, a ship, or a person belonging to the other side in a war — usually singular ▪ They targeted the enemy at close range.
▪ They are sworn/bitter enemies. ▪ He made a lot of enemies during the course of his career. ◊If you are your own worst enemy you act in a way that causes harm to yourself or to the people or things that you care about.
▪ Tradition is the enemy of progress. ▪ In many countries today, drug abuse is public enemy number one. [=the most dangerous threat to society]
b : a military force, a ship, or a person belonging to the other side in a war — usually singular ▪ They targeted the enemy at close range.
