1.
one of the jointed appendages of an animal used for locomotion or grasping: arm; leg; wing; flipper
2.
any of the main branches arising from the trunk or a bough of a tree
3.
(astronomy) the circumferential edge of the apparent disc of the sun or the moon or a planet
4.
either of the two halves of a bow from handle to tip
the upper limb of the bow
5.
the graduated arc that is attached to an instrument for measuring angles
the limb of the sextant
6.
any projection that is thought to resemble a human arm
Spiral staircases in medieval castles are running clockwise. This is because all knights used to be right-handed. When the intruding army would climb the stairs they would not be able to use their right hand which was holding the sword because of the difficulties of climbing the stairs. Left-handed knights would have had no troubles, except left-handed people could never become knights because it was assumed that they were descendants of the devil.