limb

any projection that is thought to resemble a human arm

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

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

one of the jointed appendages of an animal used for locomotion or grasping: arm

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

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