In ancient Rome, Latin has no equivalent translation for defining homosexuality, nor heterosexuality as an individual's sexual nature.
Sexuality instead is determined by behaviour mannerisms, whether masculine or passive in both male and female roles. Roman society had a patriarchal system in which the gender role of the male is the primary authority, emphasized by the "active" masculinity as a premise of governance, power and status.
In the case of the freeborn women of Rome, they were sometimes described as "tribas fricatrix", meaning "she who rubs" and "virago", from the latin word vir (virile 'man), a term used to describe a woman who demonstrates exemplary and heroic qualities.
Roman religion supported acceptance of sexuality, as an aspect that prospered religious practice for improving erotic lifestyle as well as defining an individual's power through the procreative force of the male. Such traditions were a sign of active masculinity, but whether the religious tolerance can be applicable to homosexual acts is unknown.
Men were free to have intercourse with men, but generally only acceptable in instances where the masculinity of the freeborn Roman citizen wasn't subject to the law of Lex Scantinia, otherwise bringing his name and family reputation into dis-repute or infamia (infamia – A loss of legal or social standing).
Lex Scantinia was a Roman law that historians believe was created to penalise any male citizen of high standing that took a willing role in passive sexual behaviour. From a societal perspective, to be "passive" or "submissive", threatened the very fabric of masculinity, with feminine traits, submission and passive mannerisms being an act of the lower class and slaves.
Same sex intercourse with prostitutes or slaves was actually acceptable, not vitiating on a freeborn's masculinity as long as the freeborn citizen took the active role in penetration. In rare cases, freeborns who bestowed their anal orifice or "scultima", was in florid slang a "Scultimidonus." Translated as "asshole bestower," mentioned in text from the Roman Satirist, Gaius Lucilius (c.160s – 103/2 BC).
In the legions, the act of homosexuality amongst soldiers was considered a violation of military discipline and subject to harsh penalties. Polybius (ca. 200–118 BC), a Greek Historian reported in his journals that same sex activity amongst soldiers was punishable by the fustuarium, (clubbing to death).
As with any freeborn, Soldiers were allowed to engage in same-sex relations with slaves, prostitutes and captives as a sign of inserting their sexual authority and their (active) masculinity. An incident related by Plutarch in his biography of Marius, illustrates the soldier's right to maintain his sexual integrity. In this instance, a legionnaire named Trebonius was the object of sexual assaults by his superior officer, Gaius Luscius. Trebonius was brought before a tribunal for killing Luscius, but later acquitted and awarded a crown of bravery for defending his masculinity and freeborn male purity.
In another case of same sex in the army, "De Bello Hispaniensi," a book believed to have been written by Julius Caesar (Although the authorship is heavily disputed) details Caesar's campaigns on the Iberian Peninsula and mentions a Roman officer who engages in regular sexual acts with his concubine (concubinus).
More at Roman Same-Sex, Slaves and Lex Scantiniahttp://www.heritagedaily.com/2012/02/roman-same-sex-slaves-and-lex-scantinia/