tricenarian
The highest rank and pay grade for prefectures in Ancient Rome.
Following the reign of Scptimius Severus (193-211), the emperor's patrimonium, his personal properties, was merged with a new department, the ratio privata (private accounts) headed by the magister rationis summae privatae at the tricenarian level.
A person in their thirties, a person aged between 30 and 39 years (inclusive).
« I sure hope so » agreed the tricenarian, « it would be a real shame to have been on this island without having really seen its treasures » he observed, his attitude revealing that he actually expected the unsatisfactory outcome.
Where it comes from
From Latin trīcēnārius, equivalent to tricenary + -an.
Adapted from the Wiktionary entry tricenarian (CC BY-SA 4.0).