The American Heritage Dictionary provides a good definition of wrath that aligns well with some of the comments above:
- Forceful, often vindictive anger.
He feared the wrath of his employer.
Wrath can also mean:
- Punishment or vengeance as a manifestation of anger.
He decided to risk the wrath of the authorities and go ahead with the plan.
In a religious context, wrath can also have a more specific meaning of divine retribution for wrongdoing or sin.
You broke the divine law by murdering your brother and must suffer the wrath of the Almighty.
Some sources note that wrath can imply righteous anger (similar to the above):
righteous indignation and condemnation especially of a deity or sovereign
It can also be used humorously in certain contexts:
wrath: extreme anger (chiefly used for humorous or rhetorical effect)
(Oxford American Dictionary)