[fee-nuh-thahy-uh-zeen, -zin]
Chemistry. a grayish-green to greenish-yellow, crystalline, water-insoluble solid, C 1 2 H 9 NS, used chiefly as an insecticide and vermifuge, and in the synthesis of pharmaceuticals.
Pharmacology. any of a class of medications used principally to treat psychotic symptoms, as delusions or hallucinations, and excessive excitability.

1890–95; pheno- + thiazine Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
phenothiazine (ˌfiːnəʊˈθaɪəziːn)
1.  a colourless to light yellow insoluble crystalline compound used as an anthelmintic for livestock and in insecticides. Formula: C12H9NS
2.  any of several drugs derived from phenothiazine and used as strong tranquillizers and in the treatment of schizophrenia

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

phenothiazine phe·no·thi·a·zine (fē'nō-thī'ə-zēn', -nə-)

  1. A yellow organic compound used in veterinary anthelmintics. Also called thiodiphenylamine.

  2. Any of a group of drugs derived from this compound and used as tranquilizers in the treatment of psychiatric disorders, such as schizophrenia.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
phenothiazine   (fē'nō-thī'ə-zēn')  Pronunciation Key 
  1. A yellow or green, toxic organic compound used in insecticides and dyes and to treat infections with worms and other parasites in livestock. Chemical formula: C12H9NS.

  2. Any of a group of drugs derived from this compound. Phenothiazines are dopamine antagonists and are used in the treatment of psychiatric disorders, such as schizophrenia.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica


widely used anthelmintic (worming agent) in veterinary medicine. Phenothiazine is an organic compound effective against a broad range of parasites in cattle, horses, poultry, sheep, and swine. A highly toxic drug, it is not recommended for human use and is not effective in dogs or cats

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
Phenothiazine is a medication used to treat serious mental and emotional disorders.
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