Plural of feverberry; berries or fruit that were traditionally used in folk medicine to treat fever and other ailments.
Compound of 'fever' + 'berries,' from Old English 'fefor' (fever) + berries. Folk medicinal terms became standardized in herbals and medical texts over centuries.
Many plants were named after the diseases they supposedly cured—feverberries, feverfew, feverwort—and it's interesting that some of them actually work while others are pure placebo.
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