Is a victim of mental or verbal abuse a result of one or two disagreements in which unkind words were spoken or a constant diet of insults and controlling behavior?
Everyone gets short tempered and rude at times...and human beings don't act ideally towards each other 100% of the time. An isolated incident of name calling or yelling doesn't make a person abusive, but should maybe make that person look at other ways of handling stress and conflict with a person.
But persisting in a certain type of behaviour towards someone when you are fully aware that it's causing them stress and discomfort is an abusive behavior. And while a victim may see (and attempt to deny) a pattern of these behaviors emerging in a relationship, the abuser tends to discount the behavior as abusive but as a "disagreement" "misunderstanding", etc. These "disagreements" and "misunderstandings" may pop up ever few days, weeks or months, or they may escalate in frequenty. The result is that the victim, even in the weeks or months where there is no abuse, tends to worry about the abuser's anger or possible reaction to minute incidents (missing items, broken equipment, plans changed or off schedule, etc.)