The Gerousia was the Spartan senate. Meaning Council of Elders it consisted of thirty members including the two kings. Members had to be over the age of 60 and were elected for life. Theoretically, any Spartan citizen of the right age could stand but in practice members were selected from the most important aristocratic families.
The Gerousia prepared motions or rhetrai for the wider citizen assembly, the Apella, to vote on. The Gerousia could also veto motions passed by the Apella and was consulted by the ephors in matters of interpretation of the law. Additionally, the gerousia filled the role of a court to try murder cases - and had the power to condemn, fine, or banish.
The Gerousia, or Senate, was brought back as an institution in the modern Greek state. It has since been abolished. Today, Greece has a unicameral legislature.