Q: Why do we have two words for a small island—“key” and “cay”? And are they related to “quay,” the word for a wharf?
A: “Key” and “cay” are just different spellings of the same 17th-century word for a small, low island, especially in the Caribbean or off the coast of Florida.
“Key” is more common in Florida and “cay” in the Caribbean, and it’s likely that local customs and place names have kept the different spellings alive.
As we’ll explain later, both of them are probably derived from “quay,” a word from French that means a wharf.
First let’s talk about the pronunciations.
“Key” is pronounced KEE, like the unrelated word for something that opens a lock. “Cay” is usually pronounced the same way (KEE), but some dictionaries give an alternate pronunciation, KAY.
“Quay” was originally pronounced KEE, and that’s still the preferred pronunciation (it was once spelled “key”). Some dictionaries give only that pronunciation, though in American English two variant pronunciations are recognized as standard: KAY and KWAY.
We’ll have more to say about “quay” later.
The geographical terms “key” and “cay” were “originally the same word,” according to the Oxford English Dictionary.
Although “key” was recorded in writing first (1693), Oxford says it originated as a variant spelling of “cay,” which wasn’t recorded until 1707 but was no doubt known to explorers much earlier. In 17th-century English, “key” was pronounced KAY.
Oxford defines “key” as “a low-lying island or reef, esp. in the Caribbean or off the south coast of Florida.” And it says the earlier “cay” was similarly used for “islets” of sand, mud, rock, or coral lying “around the coast and islands of Spanish America.”
Here is the dictionary’s earliest citation for “key”:
“The place whereon Port-Royal was since built, was like one of the Keys or little Islands that lie off this Harbour.” (From a letter written on July 3, 1693, and published the following year in Philosophical Transactions of the Royal Society of London.)
“Key,” as we’ve said, was originally a variant spelling of “cay.” As for “cay,” it was derived from the 16th-century Spanish word cayo (shoal or barrier reef).
That old Spanish word is “of uncertain origin,” Oxford says, but it’s “perhaps ultimately the same word as French quai … or perhaps a loanword from an indigenous language of the Antilles.”
Other etymologists are more definite about the French connection.
The American Heritage Dictionary of Indo-European Roots (2nd ed.) says that “cay,” and “key” are descended from the Old French quai, the source of “quay.”
And the French word, American Heritage adds, comes from caio (rampart or retaining wall) in Gaulish, an extinct Celtic language once spoken by Celts in what is now France, Belgium, and other parts of northern Europe.
Going even further back, etymologists have identified a prehistoric Indo-European ancestor, a root reconstructed as kagh– that meant a wickerwork or a fence. This ancient meaning is reflected in the Gaulish and early French versions of the word.
“The French word was probably originally used with reference to fence-like wooden revetments, which were used to stabilize riverbanks and allow boats to moor,” the OED explains.
When the word first came into English in 1399, the OED says, it was spelled “key” and meant “a man-made bank or landing stage” for ships, either along the water or projecting into it.
The earliest OED example is from Aberdeen, Scotland. A notation in town records for 1399 describes a contract for the construction of 12 windows and 12 doors, to be delivered by the following Easter “at ony key of Abirden, or ellis at the sandis at Lawrence of Lethis howss” (“at any key of Aberdeen, or else at the sand beach at Lawrence of Leth’s house”).
The quotation appears in Extracts From the Council Register of the Burgh of Aberdeen, 1398-1625. We’ve added a few words from the original for context.
Though this is the first known example in written English, the word was familiar in Britain much earlier through Anglo-Norman French (spellings include kaye, kaie, kei, key, and many others).
And similar-sounding words meaning a fence or enclosure—and traced to the same prehistoric Indo-European root—existed in Celtic languages spoken in Britain, like Welsh (cae) and Cornish (kē).
The spelling “quay” showed up in the mid-1500s, more than 150 years after that 1399 example, when it was borrowed from French, according to John Ayto’s Dictionary of Word Origins.
The earliest citation in the OED is from a letter written to Sir Thomas Gresham on Dec. 31, 1561, by his agent in Antwerp:
“So many Quays crowne-serchers, wayters, and other powlyng [plundering] offycers.” (The letter is about the chaotic customs searches on the London docks, as compared to more sedate Antwerp.)
Today “quay” still means what it originally meant—a wharf. But it’s always been less common in the US than in the UK, Canada, and other Commonwealth countries.
Finally, as we mentioned earlier, the “key” that opens a lock is unrelated, as far as anybody knows. It’s been traced back to Old English (caeg), but no further.
“No one knows where the word originally came from,” Ayto says, adding that “it has no living relatives in other Germanic languages.”