"Gnaw lips in rage" refers to the act of clenching one's teeth or biting one's lips in anger or frustration. Synonyms for this phrase include "grind teeth," "tighten jaw," "clamp mouth shut," "narrow eyes," "frown deeply," "scowl," and "seethe with anger." These phrases are used to describe physical manifestations of emotion and can convey a powerful sense of frustration, anger, or irritation. Whether used in literature, media, or daily conversation, these synonyms offer varied ways to describe the intense emotional response often experienced in difficult situations.