Visibly furious, with one's face flushed from intense rage or indignation.
This color-emotion association dates to ancient times and reflects the observable physiological response of increased blood flow to the face during anger. The phrase has appeared in English literature since at least the 16th century, drawing on the universal human experience of facial flushing during emotional arousal.
The connection between red and anger appears across many cultures and languages, suggesting it's based on universal human physiology rather than arbitrary cultural association. Fascinatingly, people can often detect anger in others before conscious recognition kicks in, partly by unconsciously noticing subtle changes in facial coloration.
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