A vocabulary of landscape — a landscape of words
1469 entries
gill
A gill is a respiratory organ for taking oxygen out of water, built as a stack of thin filaments with a large surface area and blood running close to the surface. The best fish gills work as a counterflow exchanger, with water moving across them in the opposite direction to the blood, which extracts far more oxygen than moving them the same way would. The word also names the radiating blades under a mushroom cap.
Etymology
English has at least three unrelated words here. The breathing organ is from Old Norse. The northern English ravine is a separate Norse word, spelled the same and pronounced the same. And a gill of liquid, a quarter of a pint, is from Old French and rhymes with Jill.
Notes
The gills of a mushroom are not for breathing. They are the spore-bearing surface, and their whole purpose is to hang enough area vertically for spores to drop off and be carried away, which is why a mushroom knocked on its side will bend its gills back to vertical within hours. The word was applied to them by analogy to the fish organ purely on the look of the thing.