Arm

1. The upper limb of a human body. He held his arm out to show it to his doctor.
2. To prepare for action. We must arm ourselves before we are attacked.
3. Something, such as a sleeve on a garment or a support on a chair, that is designed to cover or support the human arm. An arm chair aids old people to rise to their feet.
4. A relatively narrow extension jutting out from a large mass. The boat rounded an arm of the sea.
5. Power or authority. The long arm of the law will catch you eventually.
6. Slang. An excessively high price. The car will cost you and arm and a leg.
7. At a distance that physical or social contact is discouraged. She kept the new boy at arm's length at first.