Monica
I love Monica as it cannot be abbreviated and I think while feminine it is strong as I have been told it means the nun or advisor.
Monica is a very old name, and its true origin is uncertain. From early times it has been associated with either a Greek word meaning "alone," or Latin meaning "to counsel; advise." However, Monica is probably Phoenician in origin; its first recorded bearer being St. Monica from Carthage, who was also the mother of St. Augustine.