1 : sharp and harsh or unpleasantly pungent in taste or odor
2 : deeply or violently bitter
1 : Thick, acrid smoke rose from the factory.
2 : There have been acrid relations between the two families ever since they fought over that strip of land.
Another double meaning word. This one is interesting in that the first usage is pretty common, but the second is rare. It also suggests that both might be usable at the same time, to describe a rather hostile situation.