How are we defining Emperor?

Augustus wasn't known as Emperor. He was known as Imperator, sure, but so were lots of people who weren't even Consuls necessarily. I'm pretty sure Agrippa at least was granted the title by the Senate while Augustus was also an Imperatore. The power he wielded was huge, but not necessarily as great as that wielded by those with Dictatorial powers since afair Augustus specifically did not legislate those powers to himself since they were tainted with association with Lucius Cornelius Sulla.