Your arms are the two long parts of your body that are attached to your shoulders and that have your hands at the end.

The arm of a piece of clothing is the part of it that covers your arm.

The arm of a chair is the part on which you rest your arm when you are sitting down.

An arm of an object is a long thin part of it that sticks out from the main part.

An arm of land or water is a long thin area of it that is joined to a broader area.

An arm of an organization is a section of it that operates in a particular country or that deals with a particular activity.

If two people are walking arm in arm, they are walking together with their arms linked.

If you say that something costs an arm and a leg, you mean that it is very expensive.

If you hold something at arm's length, you hold it away from your body with your arm straight.

If you keep someone at arm's length, you avoid becoming too friendly or involved with them.

If you say that a list is as long as your arm, you are emphasizing that it is very long.

If you welcome some action or change with open arms, you are very pleased about it. If you welcome a person with open arms, you are very pleased about their arrival.

If you twist someone's arm, you persuade them to do something.