Prime (rank)

"We are Primus. We are Prima. We are Prime Nova. We are Sentinel Prime. We are Optimus Prime."

Prime is a rank of highest distinction in many Transformers continuities. Typically, it is used as the identification for the leader of the Autobots, something that is bestowed only on those that carry the Matrix of Leadership within them. It is retroactively derived from Primus, the creator of the Transformers.

Cartoon continuity
The evidence for "Prime" being a rank here is weaker than elsewhere but the case can still be made. Though many Matrix-Bearers are seen, and all are by definition Autobot Leaders, only four are ever named; 2 Primes, 2 not: Alpha Trion, Optimus Prime, Ultra Magnus, and Rodimus Prime. Without knowing any other names it is hard to make a concrete case here for "Prime" being a title given only to Matrix-Bearers.

It is of note though that if it were, then "Prime" in this continuity would be a military/political title (since it is the Matrix of Leadership), rather than a religious title.

Shattered Glass
The title of Prime is not an honorary rank but the title of the diabolical leader of the Autobots. Optimus Prime stands as the current Prime. For now. Rodimus, Ultra Magnus or Thunderclash may very well usurp the title and position in the future.