End of the Principate?

[Anonymous]

I'm familiar with the use of the term "Principate" with reference to the period beginning with the reign of Augustus... but I'm a little ambiguous about whether there is a date that is customarily used as its terminus point. I get the sense that at a certain point, scholars stop talking about the Principate and start talking about the "empire" but I'm not sure exactly where this point is. Can anyone clear this up for me?<br>
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Aaron <p></p><i></i>