Villi

Part of speech: noun

Definitions

1. Small, finger-like outgrowths on the surface of tissues that function to maximize absorption within the digestive tract
2. Minute, hair-like structures present on some cells that serve to improve the surface area available for nutrient absorption
3. Tiny, elongated structures projecting from tissue surfaces to increase efficiency of nutrient uptake

Etymology: "Villi" is the plural of "villus," which English borrowed directly from Latin, where "villus" meant "shaggy hair" or a tuft of hair. The image is literal: the tiny projections lining the small intestine and other body surfaces look like a coat of fine hairs, and that resemblance is what the Latin word captured long before anyone had a microscope to see them. Because "villus" is a Latin noun, its plural follows the Latin pattern, which is why English keeps "villi" rather than adding "-es" as in most native plurals. The same pattern appears in other borrowed Latin nouns such as "fungus" and "radius," whose plurals English also takes from Latin.