WordWeb Online

1. Fighting; acts of overt warfare
   "the outbreak of hostilities";
   - belligerency

1. A hostile (very unfriendly) disposition
   "he could not conceal his hostility";
   - ill will
    
2. A state of deep-seated ill-will
   - enmity, antagonism
    
3. The feeling of a hostile person
   "he could no longer contain his hostility";
   - enmity, ill will
    
4. Violent action that is hostile and usually unprovoked
   - aggression

Type of: action, armed combat, combat, hate, hatred, state, unfriendliness

Encyclopedia: Hostilities