rha·pon·tic \rəˈpäntik\noun Etymology: New Latin rhaponticum, from rha ponticum pontic rhubarb, from Late Latin rha rhubarb + Latin ponticum, neuter of ponticus pontic — more at rhubarb, pontic 1.archaic: either of two European knapweeds (Centaurea centaurium and C. rhaponticum) 2.archaic a.: a rhubarb (Rheum rhaponticum) b.: the root of this plant used in pharmacy