Is it ensure, insure, or assure?
1811, from French hyoïde (16c.), from Modern Latin hyoides, from Greek hyoeides "shaped like the letter U," from hu "letter U" (in later Greek called upsilon) + -oeides "like" (see -oid).
hyoid hy·oid (hī'oid')adj.
Shaped like the letter U.
Of or relating to the hyoid bone.