vervainPronunciation: /ˈvəːveɪn/Definition of vervain noun [mass noun] a widely distributed herbaceous plant with small blue, white, or purple flowers and a long history of use as a magical and medicinal herb. Verbena officinalis, family Verbenaceae Origin: late Middle English: from Old French verveine, from Latin verbena (see verbena)vervain in other Oxford dictionaries Definition of vervain in the US English dictionary