The Romans had no single term for the position: Latin and Greek titles such as augusta (Greek αὐγούστα, augoústa, the female form of the honorific augustus, a title derived from the name of the first emperor, Augustus), caesarea (Greek καισᾰ́ρειᾰ, kaisáreia, the female form of the honorific caesar, a title derived from the name of Julius Caesar), βᾰσῐ́λῐσσᾰ (basílissa, the female form of basileus), and αὐτοκράτειρα (autokráteira, Latin autocratrix, the female form of autocrator), were all used.

In the third century, augustae could also receive the titles of māter castrōrum "mother of the castra" and māter patriae "mother of the fatherland". Another title of the Byzantine empresses was εὐσεβέστᾰτη αὐγούστα (eusebéstatē augoústa, meaning "most pious augusta"); they were also called κῡρίᾱ (kūríā, meaning "lady"), or δέσποινα (déspoina, the female form of δεσπότης, despótēs, "despot"). Due to the practice of dividing the Roman empire under different emperors, there were periods when there were more than one Roman empress. All the Roman empresses are listed with some co-empresses. Not all empresses were titled augusta, and not all augustae were empresses since the emperor's sister or mistress could bear that title. Some caesarissas and despoinas that never were empresses are included, since the titles were quite similar to empress; however, in the Eastern Roman Empire these titles are often more equivalent to the modern term "crown princess".