Read the dictionary definition of arm. All definitions for this word.
1. the part of an armchair or sofa that supports the elbow and forearm of a seated person
2. any projection that is thought to resemble a human arm
1. the arm of the record player
2. an arm of the sea
3. a branch of the sewer
3. the part of a garment that is attached at the armhole and that provides a cloth covering for the arm
4. any instrument or instrumentality used in fighting or hunting
1. he was licensed to carry a weapon
5. 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
6. a division of some larger or more complex organization
1. a branch of Congress
2. botany is a branch of biology
3. the Germanic branch of Indo-European languages
7. prepare oneself for a military confrontation
1. The U.S. is girding for a conflict in the Middle East
2. troops are building up on the Iraqi border
8. supply with arms
1. The U.S. armed the freedom fighters in Afghanistan
See also:
Merriam-Webster definition of arm