Thyroid

How to spell thyroid

7 letters · 2 syllables

How to pronounce thyroid

Say the part in capitals loudest.

What does thyroid mean?

1. nounA gland in the neck that produces hormones regulating growth and metabolism.
2. adjectiveRelating to the thyroid gland or the shield-shaped cartilage near it.

Thyroid in a sentence

• noun

  The doctor ordered a blood test to check her thyroid function.

• adjective

  She takes a daily thyroid tablet to keep her hormone levels steady.

• noun

  An underactive thyroid can leave a person tired and prone to weight gain.

• adjective

  The thyroid cartilage forms the prominence known as the Adam's apple.

Where does thyroid come from?

Language of origin: Greek

This word comes from the Greek thyreoeides, meaning 'shield-shaped', which was built from thyreos, the word for a large oblong shield, and eidos, meaning 'form' or 'shape'. The anatomist Thomas Wharton applied the term in the seventeenth century to the gland that sits over a broad piece of cartilage in the neck, because that cartilage has a shield-like outline. The name therefore describes the shape of the surrounding structure rather than the gland itself. The classical 'th' and the 'oid' ending are typical signposts of a Greek borrowing, and the spelling has kept that Greek dress intact: the 'th' represents the Greek theta and the unstressed second half is the familiar '-oid' seen in 'asteroid' and 'spheroid'. Recognising that 'oid' part is the easiest way to fix the ending in memory.

How the word is built

• thyro- (from Greek thyreos: oblong shield)
• -oid (resembling, shaped like)