Angry brow refers to the furrowing of eyebrows due to anger or frustration. There are several synonyms that can be used to describe this facial expression. A person can have a scowling brow, a furrowed brow, a frowning brow, a menacing brow or a stern brow when they are angry. Other synonyms include a glowering brow, a darkening brow, a hardened brow or a thunderous brow. All of these words describe the same expression of anger and can be used interchangeably. It is helpful to use synonyms to avoid overusing the same word repeatedly and to add variety and depth to your writing.