ankyloglossia

noun

an·​ky·​lo·​glos·​sia ˌaŋ-kə-(ˌ)lō-ˈglä-sē-ə, -ˈglȯ- 

: limited normal movement of the tongue chiefly due to an abnormally shortened frenulum : tongue-tie

Technically known as ankyloglossia, it is a usually minor birth defect in which a flap of tissue under the tongue, called the frenum or frenulum, is too short or absent.

—C. Claiborne Ray, The New York Times