Routine, n.
Etymology: [F., fr. route a path, way, road. See Route, Roterepetition.]
1. A round of business, amusement, or pleasure, daily or frequently pursued; especially, a course of business or offical duties regularly or frequently returning.
2. Any regular course of action or procedure rigidly adhered to by the mere force of habit.
Shades of meaning
Fernald has no entry of its own for routine; he lists it under habit.
Where he writes about it:
Custom is the uniform doing of the same act in the same circumstance for a definite reason; routine is the doing of customary acts in a regular and uniform sequence and is more mechanical than custom. — from habit
It is the custom of tradesmen to open at a uniform hour, and to follow a regular routine of business until closing-time. — from habit
System is the coordination of many acts or things into a unity, and is more and better than routine. — from habit