The wardroom is the mess cabin or compartment on a warship or other military ship for commissioned naval officers above the rank of midshipman. Although the term typically applies to officers in a navy, it is also applicable to marine officers and coast guard officers in those nations that have such service branches. On larger vessels, such as aircraft carriers of the United States Navy, there may be more than one wardroom. It may also be used on stone frigates to refer to similar officer mess facilities at naval, marine, and coast guard installations ashore.

The mess is a designated area where military personnel socialize, eat and live. The term is also used to indicate the groups of military personnel who belong to separate messes, such as the officers' mess, the chief petty officer mess, and the enlisted mess. In some civilian societies this military usage has been extended to the eating arrangements of other disciplined services such as fire fighting and police forces.