Squire was a title.
After the USS Enterprise encountered the alien Trelane in 2267, Captain James T. Kirk referred to him by his rank of general, and each time, Trelane reminded him he was "Retired, (sir)." Furthermore, Trelane added that it was "Just Squire Trelane now. And you may call me Squire." After stating the request aloud, he added, "Yes, I rather fancy that." The second time, he added "But if you prefer, you may address me as the lonely Squire of Gothos, dear ladies." (TOS: "The Squire of Gothos")