Casing (noun)

A covering or outer layer for a device, structure, or object, usually for protection, decoration, or insulation.

Origin:

From the middle english word 'casing' meaning a cover or a sheath.

Examples:

1. The casing of the smartphone was made of durable metal to protect the device from damage.
2. The casing of the pipeline was covered with insulation to prevent heat loss.
3. The casing of the shotgun was ornately engraved with intricate designs.
4. The casing of the engine was removed to reveal the inner components.
5. The casing of the book was bound in leather with gold lettering on the spine.