cubit

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An ancient unit of linear measure, originally equal to the length of the forearm from the tip of the middle finger to the elbow, or about 17 to 22 inches (43 to 56 centimeters).

Century Dictionary and Cyclopedia

1. n. In anatomy: The forearm or antebrachium; the arm from the elbow to the wrist.
2. n. The inner bone of the forearm; the ulna.
3. n. A linear unit derived from the length of the forearm. The natural cubit used for measuring cloth was probably originally the length from the end of the thumb-nail to the elbow, though no cubit so short is known. The royal Egyptian cubit is, of all units of measure or weight, that one whose use can be traced back in history the furthest; for it was employed in the construction of the pyramids of Gizeh, perhaps 3500 b. c. From a number of Egyptian measuring-sticks found in the tombs, this cubit is ascertained to be equal to 20.64 English inches, or 524 millimeters. It was divided into seven palms, instead of six as the ordinary cubit was; and this was probably owing to measurements along walls with the forearm having been made by placing the hand behind the elbow and leaving it on the wall until the arm was laid down again. The Egyptian and Roman are the only ancient cubits of importance whose lengths are undisputed. The Roman cubit was 1½ Roman feet, or 17.4 English inches. Two cubits are mentioned in the Bible, for Ezekiel speaks of a cubit which is a cubit and a hand-breadth. The shorter of these cubits was probably that which in Deuteronomy is called the cubit of a man; the longer one, that which in Chronicles is called the cubit after the first measure—that is, the most ancient cubit. Julian of Ascalon speaks of two cubits in the ratio of 28 to 25. But we have no accurate knowledge of the lengths of the Hebrew cubits, since the cubit of the temple is estimated variously by high authorities, as from 19 to 26 inches. There are many cubits, ancient and modern, of widely different values.
4. n. In entomology, one of the veins, nerves, or ribs of an insect's wing; a cubital rib, succeeding the radius or sector. See phrases under cubitus.

Wiktionary

1. n. A unit of linear measure, no longer in use, originally equal to the length of the forearm.

GNU Webster's 1913

1. n. (Anat.), obsolete The forearm; the ulna, a bone of the arm extending from elbow to wrist.
2. n. A measure of length, being the distance from the elbow to the extremity of the middle finger.

WordNet 3.0

1. n. an ancient unit of length based on the length of the forearm