• synonyms


[thahy-rahy-uh-sis, thi-]
  1. crab lice infestation.
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Origin of phthiriasis

1590–1600; < Greek phtheiríāsis, equivalent to phtheír louse + -iāsis -iasis
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for phthiriasis

Historical Examples

  • It has been said that the phthiriasis of the cat is occasioned by the abundance of ricini.

    Animal Parasites and Messmates

    P. J. Van Beneden

  • As an equine disorder this kind of phthiriasis was first described by Bouley.


    T. Spencer Cobbold

  • Phthiriasis, thi-rī′a-sis, n. the lousy disease—morbus pediculosus.

  • I shall now proceed to the remaining class of diseases mistaken for Phthiriasis; those, namely, which are produced by larv.

  • Louse-infestation is known as phthiriasis in medical and veterinary terminology.

British Dictionary definitions for phthiriasis


  1. pathol the state or condition of being infested with lice; pediculosis
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Word Origin

C16: via Latin from Greek, from phtheir louse
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

phthiriasis in Medicine


(thĭ-rīə-sĭs, thī-)
  1. Infestation with lice, especially crab lice; pediculosis.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.