This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The state or quality of belonging.

"Because during periods of non-deployment, soldiers, who have developed a camaraderie within the ranks and who typically feel a strong sense of purpose while in combat, can lose that sense of what the study's authors term "belongingness and usefulness.""