Enmity

Name(s): 
Acrimony
Alienation
Animosity
Antagonism
Antipathy
Belligerence
Bitterness
Coldness
Conflict
Disaccord
Disaffinity
Disunity
Enmity
Friction
Hatred
Hostility
Incompatibility
Inhospitability
Irreconcilability
Malevolence
Malice
Quarrelsomeness
Repugnance
Soreness
Sourness
Strain
Tension
Unfriendliness
Venom
Virulence
Nature

An enemy or a foe is an individual or a group that is considered as forcefully adverse or threatening. The concept of an enemy has been observed to be "basic for both individuals and communities". The term "enemy" serves the social function of designating a particular entity as a threat, thereby invoking an intense emotional response to that entity. The state of being or having an enemy is enmity, foehood or foeship.

Source: Wikipedia

Type 
(A) Abstract fundamental problems