köken: From Middle High German wolfsmilch, from Old High German wolfesmilch, *wolfesmiluh. Equivalent to Wolf (“wolf”) + -s- + Milch (“milk”), after the plant's acrid sap. Compare Dutch wolfsmelk and Polish wilczomlecz.
köken: From Old Swedish þyril, from Old Norse þyrill, from Proto-Germanic *þwerilaz. Cognate with Norwegian Nynorsk tverel, Icelandic þyrill, Middle Low German dwiril.
köken: From llaeth (“milk”) + llys (“herb, plant”). In the case of Euphorbia, the name originates from the milky sap of these plants. Polygala vulgaris is so named because it was believed to induce milk production in cattle.
aile: llaethlys bach, llaethlys cypreswydd, llaethlys deiliog, llaethlys eiddïog, llaethlys rhuddlas, llaethlys y Balcanau, llaethlys y coed, llaethlys y môr, llaethlys yr ysgyfarnog
Literally, “light house grass”, 灯台(とうだい) (tōdai, “light house, light pole”) + 草(くさ) (kusa, “grass, plant”). The kusa changes to gusa as an instance of rendaku (連濁).