A bicameral legislature is made up of two chambers. The prefix "bi-" means two, and "camera" is Latin for chamber. Therefore, bicameral literally means "two chambers."
In a bicameral legislature, the law-making body is divided into two separate houses, each with its own membership, procedures, and often distinct functions. In Nigeria, the National Assembly is bicameral, consisting of the Senate (upper chamber, with 109 members) and the House of Representatives (lower chamber, with 360 members). Other examples include the United Kingdom Parliament (House of Lords and House of Commons) and the United States Congress (Senate and House of Representatives).
The rationale for bicameralism includes providing a system of checks within the legislature, ensuring broader representation (geographic and population-based), allowing for more thorough deliberation of legislation, and preventing hasty law-making.
A legislature with one chamber is called unicameral ("uni-" meaning one). There are no standard terms for three-chamber or four-chamber legislatures, as such arrangements do not exist in modern governance.