QUAY, a wharf or landing-place for the loading and unloading of water-borne cargo. The word, now pronounced like " key," takes the form of Fr. quai, older cay or caye, cf. Spanish cayo, a bar, barrier or reef. The earlier form in English is " kay," and it was so pronounced. " Key " was also earlier pronounced " kay," and the change in pronunciation in the one was followed also in the other. In spelling also the word was assimilated to " key," in the sense of a reef, or, especially, of the low range of reefs or islets on the coasts of Spanish America, e.g. on the coast of Florida, the chain of islets known as Florida Keys.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)