πετροσέλινον

Greek petroselinon (πετροσέλινον) is transparent once you know the parts: petros (rock, stone) plus selinon (celery, parsley — the Greeks used the same word for both). The plant grew wild on rocky ground across the eastern Mediterranean. It was not a cultivated herb at first but a foraged one, pulled from crevices in limestone and basalt. The name described the habitat: celery that grew on rocks.

The Romans adopted the plant and the word, Latinizing it to petroselinum. Pliny the Elder, writing around 77 CE, noted that parsley was used both as food and medicine. Roman cooks used it in sauces; Roman physicians prescribed it as a diuretic. The plant crossed from kitchen to pharmacy and back, as herbs tend to do. Its Latin name traveled wherever the Roman army ate.

Vulgar Latin shortened petroselinum to *petrosilium, then Old French compressed it further to peresil, then persil. Each transmission dropped syllables. By the time the word reached Middle English as persely or parsley around the 14th century, the 'rock' part — petro- — was unrecognizable. The Greek geography was buried. Nobody hearing 'parsley' thinks of stones.

Parsley became the most widely used herb in European cooking, a position it held for centuries before basil and cilantro challenged it in the 20th century. The phrase 'parsley, sage, rosemary, and thyme' — immortalized by the folk song 'Scarborough Fair' — lists the four herbs that defined English cooking for five hundred years. All four have Greek or Latin names. All four were foraged before they were farmed.