Severe or uncontrolled bleeding from blood vessels, either internally or externally.
From Greek haima (blood) + rhegnynai (to burst/break). The Latinate form became standard in medical terminology for describing different types of bleeding.
Haemorrhagia was so common in medieval battlefields that surgeons developed cauterization—literally burning wounds shut—as one of the few ways to stop bleeding when they had no other tools.
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