unfriendly or hostile relations; enmity; hostility; animosity:
When the territory was being settled there was bad blood between the farmers and the ranchers.
Origin
1815-25
British Dictionary definitions for bad blood
bad blood
noun
1.
a feeling of intense hatred or hostility; enmity
Idioms and Phrases with bad blood
bad blood
Anger or hostility between persons or groups, as in There's been bad blood between the two families for years. This term is based on the old association with blood and emotion, particularly anger. Versions such as ill blood preceded it; Charles Lamb was among the first to use the idiom in its current form in an 1823 essay.