In Hamlet, the treacherous King Claudius plans to poison Hamlet’s wine cup, saying:
“The King shall drink to Hamlet’s better breath,
And in the cup an union shall he throw…”
So what does he put in the cup? With “an” preceding the word, it looks as though he might have meant to say an “onion.” That’s hardly the thing for better breath, is it? No, actually what the King puts into the wine is a pearl—and presumably one that has been dipped in some lethal marinade.
The word union and the word onion are from the same Latin root—unionem, meaning “oneness, especially that formed by joining separate parts.” So how did this abstract concept of unity become the name of a both a precious gem and a pungent vegetable that adds zest to bland food?
Evidently the term unionem was used in colloquial Roman Latin to mean, first a pearl of high quality, believed to occur singly, and then an onion—owing to its resemblance to the pearl, plus the fact that it was formed of successive layers of skin joined into one whole, as opposed to the solid structure of its culinary mate, garlic.
By the 12th century, oignon was an Old French word for the vegetable, and in English spelled union or unyoun. By the 14th century the u had become an o, and Chaucer refers to “garleek, oynons, and lekes.” The sense of “pearl,” spelled union, remained in usage until about the 17th century.
The “pearl onions” that one sees on a toothpick in Gibson cocktails are something of a redundancy, since a pearl is an onion, and an onion is a pearl, and they are both unions.
The Bard of Buffalo Bayou is no pearl, but he does exude a certain pungency on occasion, sometimes in his verses:
I like onions, garlic, jalapeños,
Barbecue, hot wings, chiles relleños,
Corn dogs, bacon burgers, guacamole,
Tiramisu, cherry pie, cannoli,
Filet mignon, béarnaise sauce, spumoni,
Gorgonzola, Stilton, cannelloni,
Vindaloo, biryani, curry powder,
Deep-fried shrimp and scallops, lobster chowder,
Kippers, salmon, oysters, baked potatoes,
Ice cream, chocolate, and fried tomatoes.
And when at last I’ve finished all the crumbs,
I’m also fond of Rolaids and of Tums.