What is Infamia?

Legal Definition
In ancient Roman culture, infamia (in-, "not," and fama, "reputation") was a loss of legal or social standing. As a technical term of Roman law, infamia was an official exclusion from the legal protections enjoyed by a Roman citizen, as imposed by a censor or praetor. More generally, especially during the Republic and Principate, infamia was informal damage to one's esteem or reputation. A person who suffered infamia was an infamis (plural infames).

Infamia was an "inescapable consequence" for certain professionals, including prostitutes and pimps, entertainers such as actors and dancers, and gladiators. Infames could not, for instance, provide testimony in a court of law. They were liable to corporal punishment, which was usually reserved for slaves. The infamia of entertainers did not exclude them from socializing among the Roman elite, and entertainers who were "stars", both men and women, sometimes became the lovers of such high-profile figures as the dictator Sulla and Mark Antony.

A passive homosexual who was "outed" might also be subject to social infamia, though if he was a citizen he might retain his legal standing.

The modern Roman Catholic Church has a similar concept of infamy.
-- Wikipedia
Legal Definition
Lat Infamy; ignominy or disgrace. By infamia juris is meant infamy established by law as the consequence of crime; infamia facti is where the party is supposed to be guilty of such crime, but it has not been judicially proved. Comm. v. Green, 17 Mass. 515, 541.
-- Black's Law Dictionary
Legal Definition
Infamy; disgrace.
-- Ballentine's Law Dictionary