acts of overt warfare; "the outbreak of hostilities" a hostile (very unfriendly) disposition; "he could not conceal his hostility" the feeling of a hostile person; "he could no longer contain his hostility" a state of deep-seated ill-will
Hostility is unfriendly or aggressive behaviour towards people or ideas. The last decade has witnessed a serious rise in the levels of racism and hostility to Black and ethnic groups
Your hostility to something you do not approve of is your opposition to it. There is hostility among traditionalists to this method of teaching history