parsley n.

c. 1400, in anatomy, "very hard, dense," from Old French petros (Modern French petreux) and directly from Latin petrosus "stony," from petra "rock," from Greek petra "rock, cliff, ledge, shelf of rock, rocky ridge," a word of unknown etymology (Beekes says it is "probably Pre-Greek"). Used of certain bones, especially of parts of the temporal bone.

umbelliferous European plant long cultivated as food, 1660s, sellery, from French céleri (17c., originally sceleri d'Italie), said by French sources to be from Italian (Lombard dialect) seleri (singular selero), from Late Latin selinon, from Greek selinon "parsley" (in Medieval Greek "celery"), a word of uncertain origin. The c- spelling, attested by 1719 in English, is from French. Middle English words for "wild celery" were acheand selinum.

[O]ne day, in a weak and hungry moment, my roommate and I succumbed to a bit of larceny. A greengrocer's truck had parked down the street and was left unattended. We grabbed the first crate we could off the back. It turned out to be celery. For two days we ate nothing but celery and used up more calories chewing than we realized in energy. "Damn it," I said to my roommate, "What're we going to do? We can't starve." "That's funny," he replied. "I thought we could." [Chuck Jones, "Chuck Amuck," 1989]