Pissabed was once a common name for the dandelion, and a slightly less common name for other wildflowers, such as the bluet (Genus Centaurea), oxeye daisy (Leucanthemum vulgare), and buttercup (various members of the family Ranunculaceae). These were all given the name of pissabed because they were used as diuretics; they are also said to have other medical uses, and many buttercups are poisonous, so I do not recommend the medicinal usage of pissabeds based on the limited information that I give here.
The word pissabed was used in Middle English (often in the form piss-a-bed or pisse-bed), a compound word formed piss, meaning urine, and abed, referring to the garden bed. This etymology is preserved in the French word for dandelion, pissenlit (lit being French for bed).
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