What is the term for a Marine's formal dress uniform?

The formal dress uniform for a Marine is known as Dress Blues. This term specifically refers to the iconic uniform that includes a dark blue jacket, light blue trousers, and a white cover. It is worn during ceremonial occasions, formal events, and inspections, reflecting the pride and tradition of the Marine Corps.

In contrast, the Service Dress refers to a more general uniform appropriate for various duties and situations, but it may not carry the same formal connotation as Dress Blues. The Field Uniform is designed for operational use and typically involves more functional attire suitable for combat situations. Battle Dress is another term associated with combat-ready clothing but does not describe the formal aesthetics associated with the ceremonial aspect of the Marine Corps. Therefore, Dress Blues is the term that accurately captures the essence of a Marine's formal dress uniform.