Also KEY2, q.v. [ad. Sp. cayo shoal, rock, barrier-reef, OF. cay, caye sand bank or bar, in med.L. caium. Diez cites from the pseudo-Isidore Gl. kai ‘cancellæ,’ kaij ‘cancelli,’ bars, barriers; and refers it to Celtic cae, pl. caiou ‘munimenta’ in Oxf. glosses. Cf. Welsh cae hedge, Breton kaé embankment. The sense with which it was applied to the reefs, was thus that of ‘bars, barriers.’ Orig. the same word as QUAY, q.v. In 17th c. Eng., key was pronounced kay, whence, by assimilation, cay was also written key, spelling now usual in the West Indies.
A low insular bank of sand, mud, rock, coral, etc.; a sandbank; a range of low-lying reefs or rocks; orig. applied to such islets around the coast and islands of Spanish America.
1707. Sloane, Jamaica, I. Introd. 86. Called by the Spaniards Cayos, whence by corruption comes the English word Keys.
1769. Falconer, Dict. Marine (1789), Caies, a ridge of rocks, or sand-banks; called in the West Indies, keys.
1790. Beatson, Nav. & Mil. Mem., I. 134. The misfortune to lose the Tyger on a cayo near the island of Tortuga.
1858. in Merc. Mar. Mag., V. 159. The Light on Bush Cay [Florida]. Ibid. (1860), VII. 71. A beacon … has been erected on this Cay [in Australia].
1873. Act 36 & 37 Vict., c. 6 Preamb., The islands and cays commonly known and designated as the ‘Caicos Islands.’
1884. Littell’s Living Age, 674/2. The entrance from seaward into the harbor of Port Royal, is protected by cays or coral reefs, apparently not long risen above the surface.
