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See more synonyms for thyroid on Thesaurus.com
  1. of or relating to the thyroid gland.
  2. of or relating to the largest cartilage of the larynx, forming the projection known in humans as the Adam's apple.
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  1. thyroid gland.
  2. the thyroid cartilage.
  3. an artery, vein, etc., in the thyroid region.
  4. Medicine/Medical. thyroid glands
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Origin of thyroid

1685–95; variant of thyreoid < Greek thyreoeidḗs shield-shaped, equivalent to thyre(ós) oblong shield (literally, doorlike object, equivalent to thýr(a) door + -eos adj. suffix) + -oeidēs -oid
Related formsthy·roi·dal, adjectivethy·roid·less, adjectivean·ti·thy·roid, adjective, nounpost·thy·roi·dal, adjectivepre·thy·roid, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for thyroid

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British Dictionary definitions for thyroid


  1. of or relating to the thyroid gland
  2. of or relating to the largest cartilage of the larynx
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  1. See thyroid gland
  2. Also: thyroid extract the powdered preparation made from the thyroid gland of certain animals, used to treat hypothyroidism
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Word Origin

C18: from New Latin thyroidēs, from Greek thureoeidēs, from thureos oblong (literally: door-shaped) shield, from thura door
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

Word Origin and History for thyroid


1690s (in reference to both the cartilage and the gland), from Greek thyreoiedes "shield-shaped" (in khondros thyreoiedes "shield-shaped cartilage," used by Galen to describe the "Adam's apple" in the throat), from thyreos "oblong, door-shaped shield" (from thyra "door") + -eides "form, shape" (see -oid). The noun, short for thyroid gland, is recorded from 1849.

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Online Etymology Dictionary, © 2010 Douglas Harper

thyroid in Medicine


  1. The thyroid gland.
  2. The thyroid cartilage.
  3. A powdered preparation of the thyroid gland of certain domestic animals, used in the treatment of cretinism and myxedema, in certain cases of obesity, and in skin disorders.
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Related formsthyroid′ adj.thy•roidal adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

thyroid in Culture



A large gland in the neck that functions in the endocrine system. The thyroid secretes hormones that regulate growth and metabolism.

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The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.