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."