(n.) the functional parts of an organ
If you’re medically minded then you’ll likely know this one already. The parenchyma (pronounced “puh-reng-ki-mah”) are the specialized or functional parts of a bodily organ, as opposed to its surrounding connective tissues, blood supply and other supportive networks.
Adopted into English in the early 1500s, this is a term borrowed from the very earliest days of European medicine, and the first medical and anatomical textbooks of antiquity. Back then, many anatomists believed that the viscera of the human body was formed from blood, strained through internal tissues, which then coalesced and coagulated to form the larger functional organs. That theory is a little misguided (to put it lightly), but it nevertheless underpins the etymology of the term we use for these structures today: parenchyma literally means ‘poured beside’.
The prefix here is the same as in words like paranormal and parallel: para essentially meant ‘beside’ in Greek, and is used to form words with some sense of being located (literally or figuratively) alongside, yet separate to, something else.
Enkhyma (derived from khein, meaning ‘pour’) was a Greek word for a liquid infusion. It’s not the most productive of roots in terms of English words, but it crops up in a host of medical, botanical, zoological, and otherwise scientific terms like aerenchyma (air-filled plant tissue), sclerenchyma (the tough skeleton-like structure of certain corals), and panchymagogue (a medicine that dispels infected fluids or humours from the body). It’s also related to chyme, the physiological name for the fluid that passes from the stomach into the intestine during digestion. And there’s a fairly stout theory that claims this is the root of the word alchemy too (although, somewhat fittingly, the etymology of this mysterious subject remains unsolved).