A commander; a leader; an emperor; -- originally an appellation of honor by which Roman soldiers saluted their general after an important victory. Subsequently the title was conferred as a recognition of great military achievements by the senate, whence it carried wiht it some special privileges. After the downfall of the Republic it was assumed by Augustus and his successors, and came to have the meaning now attached to the word emperor.
a title which was usually honored a general after a major victory, it came to mean "emperor." (p. 152)
After winning a battle, the victorious general would be given this title as a salute from his soldiers. From the time of Julius Caesar, this title was taken as part of the long line of distinctions the emperors would assume. Often a number would appear after the title. This refered to the number of battles the emperor was credited with winning