in service—
1. (of a machine, etc.) in operation:
- The latest fighter-bomber is as fast as any fighter yet in service anywhere in the world.
2. employed as a domestic servant:
- I suppose you see it as somewhat anachronistic—a young girl “in service.”
in the service—while serving in the armed forces:
- Riggs had been wounded in the service. He was a hero and a fine young American.