ˈbiˌstȯrt, biˈs noun
( -s )
Etymology: Middle French bistorte, from (assumed) Medieval Latin bistorta, from Latin bis- + torta, feminine of tortus, past participle of torquēre to twist — more at torture
: any of several plants of the genus Polygonum ; especially : either a European herbaceous plant ( P. bistorta ) or a related American form ( P. bistortoides ) the twisted roots of which are used as astringents