n. [ F. rhubarbe, OF. rubarbe, rheubarbe, reubarbare, reobarbe, LL. rheubarbarum for rheum barbarum, Gr. &unr_;&unr_;&unr_; (and &unr_;&unr_;) rhubarb, from the river Rha (the Volga) on whose banks it grew. Originally, therefore, it was the barbarian plant from the Rha. Cf. Barbarous, Rhaponticine. ] 1. (Bot.) The name of several large perennial herbs of the genus Rheum and order Polygonaceae. [ 1913 Webster ]

2. The large and fleshy leafstalks of Rheum Rhaponticum and other species of the same genus. They are pleasantly acid, and are used in cookery. Called also pieplant. [ 1913 Webster ]

3. (Med.) The root of several species of Rheum, used much as a cathartic medicine. [ 1913 Webster ]

Monk's rhubarb. (Bot.) See under Monk. --
Turkey rhubarb (Med.), the roots of Rheum Emodi. [ 1913 Webster ]

a. Like rhubarb. [ 1913 Webster ]

n. [ F. rumb, Sp. rumbo, or Pg. rumbo, rumo, probably fr. Gr. &unr_;&unr_;&unr_; a magic wheel, a whirling motion, hence applied to a point of the compass. See Rhomb. ] (Navigation) A line which crosses successive meridians at a constant angle; -- called also rhumb line, and loxodromic curve. See Loxodromic. [ 1913 Webster ]

To sail on a rhumb, to sail continuously on one course, following a rhumb line. [ 1913 Webster ]

‖n. [ L., sumac, fr. Gr. &unr_;&unr_;&unr_;. ] (Bot.) A genus of shrubs and small treets. See Sumac. [ 1913 Webster ]

n. [ See Rusma. ] A mixtire of caustic lime and orpiment, or tersulphide of arsenic, -- used in the depilation of hides. Knight. [ 1913 Webster ]