Water is more elastic than air. Why?

Elasticity is the property of the object because of which an object offers opposition to the deformation produced by an external force, gets deformed, and regains its original shape when the external force is removed. Keep in mind that It corresponds to the resistance given by the object to the deformation and not to the easiness with which the object gets deformed.

The air gets easily compressed or expanded under the action of external force. The water can't get as easily deformed as that of air under the effect of the external force. The water offers more resistance to the deformation, and hence the water is more elastic thana the air.

Similarly, a copper wire is more elastic than a rubber band, and steel wire is more elastic than the copper wire.