Sesquialter

Part of speech: adjective, noun

Definitions

1. A mathematical proportion in which one quantity is one and a half times another, equivalent to the ratio 3:2
2. The relationship between two numbers where the first exceeds the second by half its value, expressed as a ratio of three to two
3. A proportional relationship where one term is fifty percent larger than the other, represented numerically as the ratio 3:2

Etymology: Latin speakers built "sesquialter" from two parts: "sesqui-", meaning "a half and a" (as in "one and a half"), and "alter", meaning "another" or "a second." Put together, the word described a ratio of one whole to one and a half parts, the kind of relationship a musician or mathematician would measure out by counting a whole and then half of it again. The compound is a straightforward one, and its history is largely contained in its parts. "Sesqui-" appears in other English words such as "sesquicentennial," a hundred-and-fifty-year anniversary, which shows the same "and a half" sense at work. The second element, "alter," is the ordinary Latin word for "other," the source of English "alter" in the sense of changing something into another thing.