What lubricates the freely movable joint at the shoulder?

Explanation

### Step-by-Step Solution:

1. **Identify the Joint Type**: The shoulder joint is classified as a ball-and-socket synovial joint. This type of joint allows for a wide range of movement in multiple directions.

2. **Understand Joint Lubrication**: In synovial joints, lubrication is crucial for smooth movement. The lubrication helps to reduce friction between the moving parts of the joint.

3. **Identify the Lubricant**: The lubricant found in the shoulder joint is called synovial fluid. This fluid is essential for the proper functioning of the joint.

...