Definition of AVAILABILITY. 1. : the quality or state of being available. 2. : an available person or thing.
Definition of EXECUTIVE OFFICER. : the officer second in command of a military or naval organization or vessel. ADVERTISEMENT. the officer second in command of a military or naval organization or vessel. ADVERTISEMENT.
The executive officer, or XO, is in charge of an Army unit's administrative operations and is usually the second-ranked officer in the unit. Executive officers often start at the company level, which has 110 to 140 soldiers, and move all the way up to the brigade level, which has 3,000 to 5,000 soldiers. Whether the XO is a first lieutenant with a company or a lieutenant colonel with a brigade, many of the duties are similar.