Relegation means being moved down to a lower level, group, or rank. It's most often heard in sports, especially football/soccer in places like the UK — a team that plays badly all season faces relegation, meaning they drop down to a lower league next season. More generally, it can describe any job, task, or thing being pushed down to less importance.

（運動）降級；（一般）被貶低地位、被排到次要位置