Definition of "Limb" :

noun: any projection that is thought to resemble a human arm

noun: the graduated arc that is attached to an instrument for measuring angles

"The limb of the sextant."

noun: either of the two halves of a bow from handle to tip

"The upper limb of the bow."

noun: one of the jointed appendages of an animal used for locomotion or grasping: arm; leg; wing; flipper

noun: (astronomy) the circumferential edge of the apparent disc of the sun or the moon or a planet

noun: any of the main branches arising from the trunk or a bough of a tree