Sandbag (noun)

1. A bag, typically made of hessian or plastic, filled with sand and used for making walls or as a means of flood protection.
2. A bag filled with sand or other material and used as a weight or to increase resistance during exercise.
3. A punch or strike delivered with a sandbag.

Origin:

Mid 19th century: from the practice of filling bags with sand for use as ballast or fortification.

Examples:

1. The residents used sandbags to protect their homes from the flood.
2. The soldiers used sandbags to build fortifications.
3. The boxer practiced hitting a sandbag to increase his punching power.
4. The weightlifter used a sandbag to increase resistance during his workout.
5. A sandbag wall was built to protect the city from the river's flood.