The Nigeria attained republican status through the 1963 constitution means that it

The Nigeria attained republican status through the 1963 constitution means that it severed the remaining links with the British monarch. This means that Nigeria was no longer a British colony and became an independent nation with its own head of state, rather than being ruled by the British monarch as a constitutional monarchy. The constitution also introduced the executive presidential system of government, created a federal system of government, and introduced a multi-party system, but these changes are not directly related to Nigeria becoming a republic.