| rhubarb | 1. <botany> The name of several large perennial herbs of the genus Rheum and order Polygonaceae. 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. 3. <medicine> The root of several species of Rheum, used much as a cathartic medicine. Monk's rhubarb. Origin: F. Rhubarbe, OF. Rubarbe, rheubarbe, reubarbare, reobarbe, LL. Rheubarbarum for rheum barbarum, Gr. (and) 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. Source: Websters Dictionary (01 Mar 1998) |
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| rhumb | <astronomy> A line which crosses successive meridians at a constant angle; called also rhumb line, and loxodromic curve. See Loxodromic. To sail on a rhumb, to sail continuously on one course, following a rhumb line. Origin: F. Rumb, Sp. Rumbo, or Pg. Rumbo, rumo, probably fr. Gr. A magic wheel, a whirling motion, hence applied to a point of the compass. See Rhomb. Source: Websters Dictionary (01 Mar 1998) |
| rhus | <botany> A genus of shrubs and small treets. See Sumac. Origin: L, sumac, fr. Gr. Source: Websters Dictionary (01 Mar 1998) |
| rhus dermatitis | Contact dermatitis caused by cutaneous exposure to urushiol from species of Toxicodendron (Rhus), such as poison ivy, oak, or sumac. (05 Mar 2000) |
| Rhus toxicodendron antigen | An extract of fresh leaves of poison ivy, with 0.4% of procaine hydrochloride; used by intradermal injection to determine sensitiveness to the poison of Rhus toxicodendron. (05 Mar 2000) |
| Rhus venenata antigen | An extract of fresh leaves of poison sumac; used to determine sensitiveness to the plant or to relieve the dermatitis caused by contact with its leaves. (05 Mar 2000) |
| rhusma | <alchemy> A mixtire of caustic lime and orpiment, or tersulphide of arsenic, used in the depilation of hides. See: Rusma. (23 Aug 1998) |