St. John's wort UK /sən(t)ˈd͡ʒɒnz wɜːt/US /seɪnt ˈd͡ʒɑnz wɝt/ noun2 •Any of several plants, of the genus Hypericum, especially Hypericum perforatum, that have yellow flowers and traditionally ward off evil.that hearbe we call S. John] — 1612 •The plant prepared as a medication. formsSt John's worts · St. John's worts
