In the days of the roman empire, it was a partial citizenship granted to some
territories in Italy and other conquered provinces. It conferred part of
the rights a full citizen had, such as the right to enter into a legal contract
with a citizen, right to defense in the roman courts and the right to appeal
capital convictions. They could also marry full citizens and be part of
the army. The only right that was denied to them was the right to be part
of the roman senate, thus they could not vote, form part of a jury or be elected
to any other roman government office.
Source: The First Man in Rome. Colleen McCullough. Avon
Books. ISBN: 0-380-71081-1. Glossary.