Bitter conflict, sometimes violent.
A trouble of any kind.
Striving; earnest endeavor; hard work.
Exertion or contention for superiority, either by physical or intellectual means.
A bitter, destructive feud, normally between two families, clans, or factions, in which each injury or slaying is revenged: a blood feud.
Revenge.
A motivational grudge against a person or faction, which may or may not be reciprocated; the state of having it in for someone.