The Latin word imperator was originally a title roughly equivalent to commander under the Roman Republic. Later it became a part of the titulature of the Roman Emperors as part of their cognomen. The English word emperor derives from imperator via Old French Empereür. The Roman emperors themselves generally based their authority on multiple titles and positions, rather than preferring any single title. Nevertheless, imperator was used relatively consistently as an element of a Roman ruler's title throughout the principate (derived from princeps, from which prince in English is derived) and the dominate.
In Latin, the feminine form of imperator is imperatrix, denoting a ruling female.
When Rome was ruled by kings, to be able to rule, the king had to be invested with the full regal authority and power. So, after the comitia curiata, held to elect the king, the king also had to be conferred the imperium.
In Roman Republican literature and epigraphy, an imperator was a magistrate with imperium (Rivero, 2006). But also, mainly in the later Roman Republic and during the late Republican civil wars, imperator was the honorifical title assumed by certain military commanders. After an especially great victory, an army's troops in the field would proclaim their commander imperator, an acclamation necessary for a general to apply to the Senate for a triumph. After being acclaimed imperator, the victorious general had a right to use the title after his name until the time of his triumph, where he would relinquish the title as well as his imperium.
SS Imperator was an ocean liner built for the Hamburg America Line (Hamburg Amerikanische Paketfahrt Aktien Gesellschaft, or HAPAG), launched in 1912. Upon launch, she surpassed the just completed RMS Titanic by 24 ft., and she herself was surpassed the same year by SS Vaterland (later SS Leviathan) by 44 ft. She was the first of a trio of successively larger Hamburg America ships that included SS Vaterland and SS Bismarck built by the line for transatlantic passenger service. At the time of her completion in June 1913, she was the largest passenger ship in the world, surpassing the Titanic's sister ship the Olympic.
During World War I, the ship remained in port in Hamburg. After the war, she was briefly commissioned into the United States Navy as USS Imperator (ID-4080) and employed as a transport, returning American troops from Europe. Following her U.S. Navy service, Imperator was handed over to Britain's Cunard Line as part of war reparations, and she sailed as the flagship RMS Berengaria for the final decade of her career.
Imperator is a genus of fungi in the family Boletaceae. It was circumscribed in 2015 by Boris Assyov and colleagues. The erection of Imperator follows recent molecular studies that outlined a new phylogenetic framework for the Boletaceae. The type species is Imperator torosus, an "impressive and prestigious" species to which the generic name Imperator refers.
The following species have been reclassified in the new genus.