Quadrans

Part of speech: noun

Definitions

1. A small bronze coin used in ancient Rome valued as one quarter of a larger unit of currency known as an as ; a unit of angle measurement in Roman times equal to one quarter of a full circle or 90 degrees
2. An ancient Roman copper coin serving as one quarter of the as in value ; a quarter section of a circle used as a measure of angles in classical Roman geometry
3. A fractional bronze coin from Rome representing one fourth of the as currency ; a classical measure dividing a circle into four equal parts, each part measuring 90 degrees

Etymology: The Roman quadrans was a small bronze coin worth a quarter of an as, the basic unit of Roman bronze currency. Its name comes straight from the Latin word for "a quarter," built on "quattuor," meaning "four," so the coin was named for its fraction rather than for any picture or ruler stamped on it. The word's English cousin is "quadrant," and the two are doublets: both descend from the same Latin noun but reached English by different routes, one absorbed into the language as a learned term and the other carried in as a specialist word. That shared ancestry explains why the same Latin word ended up naming both a tiny copper coin and a quarter-circle instrument. The angle sense, a quarter of a full circle or 90 degrees, follows the same logic as the coin: a fourth part of a whole.