1690s (in reference to both the cartilage and the gland), from Greek thyreoeides "shield-shaped" (in khondrosthyreoeides "shield-shaped cartilage," used by Galen to describe the "Adam's apple" in the throat), from thyreos "oblong, door-shaped shield" (from thyra "door," from PIE root *dhwer- "door, doorway") + -eides "form, shape" (see -oid). The noun, short for thyroid gland, is recorded from 1849.
constellation, added 1687 by Polish astronomer Johannes Hevelius, originally Scutum Sobiescanum "Shield of (King John) Sobeski," the 17c. Polish monarch famous as the savior of Christendom for his victory over the Ottomans at the Battle of Vienna (1683). The name was later shortened. From Latin scutum "shield" (see escutcheon). Middle English had scutifer "shield-bearer (late 14c.), from Medieval Latin.
dormant volcano in Tanzania, it is the highest mountain in Africa. The name is of unknown origin; the first element appears to be Swahili kilima "(little) mountain," but even this is uncertain. See J.A. Hutchinson, "The Meaning of Kilimanjaro," in Tanganyika Notes and Records, 1965.