n (mathematics) the shortest line between two points on a mathematically defined surface (as a straight line on a plane or an arc of a great circle on a sphere)
n a large edible clam found burrowing deeply in sandy mud along the Pacific coast of North America; weighs up to six pounds; has siphons that can extend to several feet and cannot be withdrawn into the shell
n Welsh chronicler who wrote an account of the kings of Britain which is now believed to contain little historical fact but it is a source of the Arthurian legend (circa 1100-1154)