Romanitas has been described aptly as not the shared biological traits of ‘a specific group’, but the fluid characteristics ‘that made a man Roman, made him an appropriate husband, father, general, and politician, and which distinguished him from a woman, child, barbarian or slave’. Moreover, different ethnic groups and regional identities could appropriate and shape ‘the form in which Romanitas was expressed in different places and in different circumstances’. In other words, Roman identity represents a flexible concept that over time meant distinct things to diverse peoples.
Admittedly, ancient references to Romanitas are not common. As Guy Halsall notes, it appears more frequently in the works of modern academics than in the ancient sources. Our first evidence of its use comes from a early third-century harangue, where the Christian writer Tertullian ridiculed the men of Carthage for aping Roman culture. Yet, despite its rarity, Romanitas captures the ancient Romans’ sense of ‘us’ versus ‘them’, and consequently, provides a valuable tool for one hoping to recover the nuanced ways individuals regarded themselves and others as Romans/non-Romans and manly/unmanly men. It also captures the Romans’ androcentrism. Following recent scholarship’s lead, I use the expression ‘manly Romanitas’ in my own work as a way to convey this intimate relationship between Romanitas and existing codes of idealised masculinity.
Although there is no precise counterpart in ancient Greek to Romanitas, the adverb, Ῥωμᾰϊκῶς, with its meaning ‘in the Roman fashion’, comes close to capturing its essence. As Ionnas Smarnakis comments, through its long history, vital facets of their identity remained linked to the Byzantines lingering sense of Romanitas:
The traditional Byzantine concept of the term “Roman”, which defined their own God-protected empire and emphasized the Roman and Christian roots of the imperial ideology, underwent several changes through the centuries. Besides its strong political content, romanitas eventually came to encompass a vast body of different, changing, and often overlapping meanings: it stressed the contrast between civilized” Romans and “uncivilized” barbarians; it declared a political identification with the Roman state; and finally, it referred to an ethnic group of people who believed that they had a common origin, spoke the same Greek language and followed the Christian Orthodox religion.
 A. Merrills and R. Miles, The Vandals (London, 2010), pp. 88-9.
 The notion that Roman identity represented primarily an ideal of the ruling elite is posed by I. Stouraitis, ‘Roman Identity in Byzantium: A Critical Approach’, Byzantion 107 (2014): pp. 55-7. Though not without its merits, this position, to my mind, too readily dismisses the lower-classes sense of Roman identity.
 G. Halsall, ‘The Barbarian Invasions,” in NCMH, ed P. Fouracre (Cambridge, 2005), p. 40.
 Tertullian, De pallio 4.1, quoted and trans in P. McKechnie, ‘Tertullian’s De Pallio and Life in Roman Carthage’, Prudentia 24 2 (1992), pp. 57-8: ‘Why at this time, if Romanness is salvation for everything, are you still not taking honourable attitudes towards the Greeks? [quid nunc, si est Romanitas omni salus, nec honestis tamen modis ad Graios estis?’].
As Andy Merrills explains (The Vandals, pp. 88-9), by the fifth century, Romanitas ‘was based overwhelmingly upon certain notions of appropriate male behaviour’.
 For the early Byzantines emphasise on the religious and political aspects of Romanitas, see C. Rapp, ‘Hellenic Identity, Romanitas, and Christianity’, in Hellenisms: Culture, Identity, and Ethnicity from Antiquity to Modernity, ed K. Zacharia (Burlington, VT, 2008), pp. 127-47.
 I. Smarnakis, Rethinking Roman Identity after the Fall (1453): Perceptions of ‘Romanitas’ by Doukas -and Sphrantzes’, Byzantina Symmeikta 25 (2015), pp. 212-13.