Since the 1500s, the word “periwinkle” has been used as the name of two distinctive items: an edible sea snail and a broadleaf evergreen plant—or, in its adjective form, the color of the flowers of said evergreen plant. Interestingly, each of these two nouns comes from a distinct root with disparate (though not entirely unrelated) origins.
The name of the plant is a diminutive form of the 12th century English word parvink, which is derived from the Old English word perwince, which is in turn derived from pervinca, the Late Latin word for the periwinkle plant. Pervinca is likely derived from the verb pervincire, which means “entwine” or “bind.” More literally, pervincire could be read as “thoroughly bound,” from per- (“thoroughly”) and vincire (“to bind or fetter”). This root presumably refers to the way the creeping plant grows, thickly and carpet-like, across the ground or other surfaces, entwining anything in its path.
What does that have to do with snails, you ask? The common periwinkle is a marine mollusk native to the northeastern Atlantic Ocean, particularly the European coastline, though they can now be found on North American coastlines as well, perhaps having traveled over while attached to mid-19th Century sea vessels.
These hitchhiking gastropods were likely called periwinkles as a cultural variation on their Old English name, pinewincle. With entirely different origins from parvink, pinewincle is composed of the Old English pine-, which is derived from the Latin word pina (“mussel,” originally from the Greek pine)—and wincel, which means “spiral shell” and comes from the Proto-Germanic prefix winkil- (bend, curve).
While it’s fascinating that two words implying curling, bending, binding and entwining came from entirely different origins, it’s not entirely clear why these two nouns converged into a homonym/graph/phone. It seems likely that it’s due to the similarity between the sounds and meanings—particularly those of the diminutive attribute of the plant’s name that implies its entwining growth (“winkle” from Latin) and the portion of the snail’s name that describes its curved shell (the Old English-Germanic “wincel” turned “winkle”).
So, if you’ve ever asked yourself that age-old question, “What the heck do flowers and snails have in common?” the answer is periwinkle.
Edit: Thanks to astute commenters, the featured image has been changed to that of a periwinkle flower.
Learn more in Once Upon a Word: An Etymology Dictionary for Kids (Rockridge Press 2020).