Vesicularity

Part of speech: noun

Definitions

1. The characteristic of containing small cavities or bubbles within a material, often seen in volcanic rocks
2. A quality describing the abundance of tiny hollow spaces or vesicles inside a solid substance
3. The state of having numerous small openings or vesicles, typically observed in certain geological formations

Etymology: "Vesicularity" is a straightforward formation: it joins "vesicular," an adjective describing things full of small hollow sacs, to the suffix "-ity," which turns an adjective into a noun naming a quality. The result names the condition of being vesicular, so a rock pocked with gas bubbles or a tissue dotted with fluid-filled sacs could both be described in terms of their vesicularity. The base word is the important part. "Vesicular" comes from the Latin "vesicula," a diminutive of "vesica," meaning bladder or blister, and that Latin root is the source of "vesicle" as well. The suffix "-ity" comes through Old French from Latin "-itas," and it is one of the most productive ways English builds abstract nouns from adjectives, as in "solidity" or "density." The word therefore adds one layer to a much older chain: a Latin word for a bladder, shaped into an adjective, then into a quality noun.