Thyroid \Thy"roid\, a. [Gr. ? shield-shaped; ? a large, oblong shield (from ? a door) + ? form: cf. F. thyro["i]de, thyr['e]o["i]de.]

1. Shaped like an oblong shield; shield-shaped; as, the thyroid cartilage.

2. (Anat.) Of or pertaining to the thyroid body, thyroid cartilage, or thyroid artery; thyroideal.

Thyroid cartilage. See under Larynx.

Thyroid body, or Thyroid gland (Anat.), a glandlike but ductless body, or pair of bodies, of unknown function, in the floor of the mouth or the region of the larynx. In man and most mammals it is a highly vascular organ, partly surrounding the base of the larynx and the upper part of the trachea.

Source: Webster's Revised Unabridged Dictionary (1913)