Definition of "Arm" :
noun: the part of an armchair or sofa that supports the elbow and forearm of a seated person
noun: any projection that is thought to resemble a human arm
"The arm of the record player."
noun: the part of a garment that is attached at the armhole and that provides a cloth covering for the arm
noun: any instrument or instrumentality used in fighting or hunting
noun: a human limb; technically the part of the superior limb between the shoulder and the elbow but commonly used to refer to the whole superior limb
noun: a division of some larger or more complex organization
verb: prepare oneself for a military confrontation
verb: supply with arms
"The U.S. armed the freedom fighters in Afghanistan."