worrying about one's master; devoted servant
Refers to a servant's deep concern for their master's well-being or affairs; can also denote the person who feels such devotion. Archaic flavor, associated with feudal loyalty.
That retainer was deeply devoted to his master, always worrying about his lord's health.
The loyal retainer, ever concerned for his master, risked his life to save his lord from danger.
Compound of 主 (しゅう, 'master') and 思い (おもい, 'thought, concern'). The reading しゅう for 主 is an older Sino-Japanese reading used in compounds related to lords or masters.