What is Much Obliged?
1.
Much obliged means that whatever was done is appreciated. Literally, it could be extended to mean that the person that says "Much obliged" now owes the other a favor. That the one that is obliged is under an obligation to pay back. Most people wouldn't expect a return favor though.
If a man is given a ride into town, when he gets out of the car, he might say "Much obliged". That would mean: "thank you for the ride. I am appreciative"
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2.
An old way of saying
Jeeves: I've finished tarring the roof of the estate, sir.
Rich guy: Much obliged, Jeeves.
Jeeves: Thank you, sir.
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