A lyre was a stringed musical instrument from Earth, similar to a harp, with a history dating back ancient Greece. The Greek god Apollo was known for his skill with the bow and lyre, according to USS Enterprise A&A officer, Carolyn Palamas.
Such an instrument sat to the side at Apollo's temple during the Enterprise's encounter with Apollo at Pollux IV in 2267. However, he did not play it, not even to Carolyn, and it was destroyed along with the temple. (TOS: "Who Mourns for Adonais?")