noun
senior councillor; member of the shogun's council of elders
Historical term for a high-ranking official in the Edo-period shogunate. The reading ろうぢゅう is a historical kana spelling.
江戸時代、老中は幕府の重要な政策決定に関わった。
In the Edo period, the rōjū were involved in important policy decisions of the shogunate.
From 老 (elder) + 中 (middle, inside), referring to senior members within the shogun's council.