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[rahy-sin, ris-in] /ˈraɪ sɪn, ˈrɪs ɪn/
noun, Chemistry.
a white, poisonous, protein powder from the bean of the castor-oil plant.
Origin of ricin
1895-1900; < New Latin Ricinus name of genus, Latin: castor-oil plant Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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  • By George, though, that Paoli must be a clever one—think of his knowing about ricin.

    The Silent Bullet Arthur B. Reeve
British Dictionary definitions for ricin


/ˈraɪsɪn; ˈrɪs-/
(biochem) a highly toxic protein, a lectin, derived from castor-oil seeds: used in experimental cancer therapy
Word Origin
C19: from New Latin Ricinus genus name, from Latin: castor-oil plant
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for ricin

poison obtained from the castor-oil bean, 1888, from ricinus, genus name of the castor-oil plant (1694), from Latin ricinus (Pliny), of uncertain origin, perhaps the same word as ricinus "tick" (in sheep, dogs, etc.).

Online Etymology Dictionary, © 2010 Douglas Harper
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ricin in Medicine

ricin ri·cin (rī'sĭn, rĭs'ĭn)
A poisonous protein that is extracted from the castor bean and is used as a biochemical reagent.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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ricin in Science
  (rī'sĭn, rĭs'ĭn)   
An extremely poisonous protein extracted from the castor bean. Ricin inhibits protein synthesis in cells, and is used as a biochemical reagent and in cancer research.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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