thyroid

1 of 2

noun

thy·​roid ˈthī-ˌrȯid 

1

: a large bilobed endocrine gland of vertebrates lying at the anterior base of the neck and producing especially the hormones thyroxine and triiodothyronine

2

: a preparation of the thyroid gland of various domestic animals used in treating thyroid disorders

thyroid

2 of 2

adjective

thy·​roid ˈthī-ˌrȯid 

variants or less commonly thyroidal

thī-ˈrȯi-dᵊl 

1

a

: of, relating to, or being the thyroid gland

b

: suggestive of a disordered thyroid

a thyroid personality

2

: of, relating to, or being the chief cartilage of the larynx

Examples of thyroid in a Sentence

Recent Examples on the Web

Noun

Hormone Fluctuations Hormonal fluctuations related to menstruation, menopause, or thyroid function can cause water retention. —Lauren O'Connor, Health, 22 Oct. 2025

For example, sleep disorders, depression or anxiety, medication side effects, infections, thyroid or vitamin issues, and other types of dementia could all potentially cause cognitive changes. —Tom Gavin, EverydayHealth.com, 20 Oct. 2025

Adjective

More:Alexis Ohanian had surgery to remove thyroid nodules that would 'likely turn cancerous' There are numerous approaches to treating hyperthyroidism, from taking anti-thyroid medications to undergoing radioactive iodine therapy. —Caroline C. Boyle, USA TODAY, 10 Jan. 2025

Arizona's top attorney sued a thyroid drug maker, saying the company lied about the potency of its medication and the harmful effects on consumers. —Taylor Seely, The Arizona Republic, 30 Dec. 2022

Word History

Etymology

Noun

short for thyroid gland — more at thyroid entry 2

Adjective

borrowed from New Latin thyroīdēs, shortened from thyreoīdēs, borrowed from Greek thyreoeidḗs "shield-shaped (of the cartilage in the larynx)," from thyreós "stone put against a door to keep it shut, oblong shield" (probably originally noun derivative of an adjective meaning "shaped like a door," from thýra "door" + -eos, suffix of appurtenance) + -oeidēs -oid entry 2 — more at door

Note: The form thyroīdēs presumably arose because the word was taken as directly derived from thýra "door," rather than from thyreós. The word thyroeidḗs "like a door" is marginally attested in ancient Greek.

First Known Use

Noun

1787, in the meaning defined at sense 1

Adjective

circa 1741, in the meaning defined at sense 1a

Phrases Containing thyroid

• thyroid-stimulating hormone
• thyroid storm

Rhymes for thyroid

• antithyroid
• hyperthyroid
• hypothyroid
• parathyroid
• euthyroid

Kids Definition

thyroid

1 of 2 adjective

thy·​roid ˈthī-ˌrȯid 

: of, relating to, or being the thyroid gland

thyroid

2 of 2 noun

: a large endocrine gland at the base of the neck of most vertebrates that produces iodine-containing hormones (as thyroxine) that affect growth, development, and metabolism

called also thyroid gland

Medical Definition

thyroid

1 of 2 adjective

thy·​roid ˈthī-ˌrȯid 

variants also thyroidal

thī-ˈrȯid-ᵊl 

1

a

: of, relating to, affecting, or being the thyroid gland

thyroid disorders

2

: of, relating to, or being the thyroid cartilage

thyroid

2 of 2 noun

1

: a large bilobed endocrine gland of craniate vertebrates that arises as a median ventral outgrowth of the pharynx, lies in the anterior base of the neck or anterior ventral part of the thorax, is often accompanied by lateral accessory glands sometimes more or less fused with the main mass, and produces especially the hormones thyroxine and triiodothyronine

called also thyroid gland

2

: a preparation of the thyroid gland of various domesticated food animals (as pigs) containing approximately ¹/₁₀ percent of iodine combined in thyroxine and used in treating thyroid disorders

called also thyroid extract